• STL algorithm源代码:stl_algo.h


    <span style="font-size:18px;">// Algorithm implementation -*- C++ -*-
    
    // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
    // 2010, 2011
    // Free Software Foundation, Inc.
    //
    // This file is part of the GNU ISO C++ Library.  This library is free
    // software; you can redistribute it and/or modify it under the
    // terms of the GNU General Public License as published by the
    // Free Software Foundation; either version 3, or (at your option)
    // any later version.
    
    // This library is distributed in the hope that it will be useful,
    // but WITHOUT ANY WARRANTY; without even the implied warranty of
    // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    // GNU General Public License for more details.
    
    // Under Section 7 of GPL version 3, you are granted additional
    // permissions described in the GCC Runtime Library Exception, version
    // 3.1, as published by the Free Software Foundation.
    
    // You should have received a copy of the GNU General Public License and
    // a copy of the GCC Runtime Library Exception along with this program;
    // see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
    // <http://www.gnu.org/licenses/>.
    
    /*
     *
     * Copyright (c) 1994
     * Hewlett-Packard Company
     *
     * Permission to use, copy, modify, distribute and sell this software
     * and its documentation for any purpose is hereby granted without fee,
     * provided that the above copyright notice appear in all copies and
     * that both that copyright notice and this permission notice appear
     * in supporting documentation.  Hewlett-Packard Company makes no
     * representations about the suitability of this software for any
     * purpose.  It is provided "as is" without express or implied warranty.
     *
     *
     * Copyright (c) 1996
     * Silicon Graphics Computer Systems, Inc.
     *
     * Permission to use, copy, modify, distribute and sell this software
     * and its documentation for any purpose is hereby granted without fee,
     * provided that the above copyright notice appear in all copies and
     * that both that copyright notice and this permission notice appear
     * in supporting documentation.  Silicon Graphics makes no
     * representations about the suitability of this software for any
     * purpose.  It is provided "as is" without express or implied warranty.
     */
    
    /** @file bits/stl_algo.h
     *  This is an internal header file, included by other library headers.
     *  Do not attempt to use it directly. @headername{algorithm}
     */
    
    #ifndef _STL_ALGO_H
    #define _STL_ALGO_H 1
    
    #include <cstdlib>             // for rand
    #include <bits/algorithmfwd.h>
    #include <bits/stl_heap.h>
    #include <bits/stl_tempbuf.h>  // for _Temporary_buffer
    
    #ifdef __GXX_EXPERIMENTAL_CXX0X__
    #include <random>     // for std::uniform_int_distribution
    #include <functional> // for std::bind
    #endif
    
    // See concept_check.h for the __glibcxx_*_requires macros.
    
    namespace std _GLIBCXX_VISIBILITY(default)
    {
    _GLIBCXX_BEGIN_NAMESPACE_VERSION
    
      /// Swaps the median value of *__a, *__b and *__c to *__a
      template<typename _Iterator>
        void
        __move_median_first(_Iterator __a, _Iterator __b, _Iterator __c)
        {
          // concept requirements
          __glibcxx_function_requires(_LessThanComparableConcept<
    	    typename iterator_traits<_Iterator>::value_type>)
    
          if (*__a < *__b)
    	{
    	  if (*__b < *__c)
    	    std::iter_swap(__a, __b);
    	  else if (*__a < *__c)
    	    std::iter_swap(__a, __c);
    	}
          else if (*__a < *__c)
    	return;
          else if (*__b < *__c)
    	std::iter_swap(__a, __c);
          else
    	std::iter_swap(__a, __b);
        }
    
      /// Swaps the median value of *__a, *__b and *__c under __comp to *__a
      template<typename _Iterator, typename _Compare>
        void
        __move_median_first(_Iterator __a, _Iterator __b, _Iterator __c,
    			_Compare __comp)
        {
          // concept requirements
          __glibcxx_function_requires(_BinaryFunctionConcept<_Compare, bool,
    	    typename iterator_traits<_Iterator>::value_type,
    	    typename iterator_traits<_Iterator>::value_type>)
    
          if (__comp(*__a, *__b))
    	{
    	  if (__comp(*__b, *__c))
    	    std::iter_swap(__a, __b);
    	  else if (__comp(*__a, *__c))
    	    std::iter_swap(__a, __c);
    	}
          else if (__comp(*__a, *__c))
    	return;
          else if (__comp(*__b, *__c))
    	std::iter_swap(__a, __c);
          else
    	std::iter_swap(__a, __b);
        }
    
      // for_each
    
      /// This is an overload used by find() for the Input Iterator case.
      template<typename _InputIterator, typename _Tp>
        inline _InputIterator
        __find(_InputIterator __first, _InputIterator __last,
    	   const _Tp& __val, input_iterator_tag)
        {
          while (__first != __last && !(*__first == __val))
    	++__first;
          return __first;
        }
    
      /// This is an overload used by find_if() for the Input Iterator case.
      template<typename _InputIterator, typename _Predicate>
        inline _InputIterator
        __find_if(_InputIterator __first, _InputIterator __last,
    	      _Predicate __pred, input_iterator_tag)
        {
          while (__first != __last && !bool(__pred(*__first)))
    	++__first;
          return __first;
        }
    
      /// This is an overload used by find() for the RAI case.
      template<typename _RandomAccessIterator, typename _Tp>
        _RandomAccessIterator
        __find(_RandomAccessIterator __first, _RandomAccessIterator __last,
    	   const _Tp& __val, random_access_iterator_tag)
        {
          typename iterator_traits<_RandomAccessIterator>::difference_type
    	__trip_count = (__last - __first) >> 2;
    
          for (; __trip_count > 0; --__trip_count)
    	{
    	  if (*__first == __val)
    	    return __first;
    	  ++__first;
    
    	  if (*__first == __val)
    	    return __first;
    	  ++__first;
    
    	  if (*__first == __val)
    	    return __first;
    	  ++__first;
    
    	  if (*__first == __val)
    	    return __first;
    	  ++__first;
    	}
    
          switch (__last - __first)
    	{
    	case 3:
    	  if (*__first == __val)
    	    return __first;
    	  ++__first;
    	case 2:
    	  if (*__first == __val)
    	    return __first;
    	  ++__first;
    	case 1:
    	  if (*__first == __val)
    	    return __first;
    	  ++__first;
    	case 0:
    	default:
    	  return __last;
    	}
        }
    
      /// This is an overload used by find_if() for the RAI case.
      template<typename _RandomAccessIterator, typename _Predicate>
        _RandomAccessIterator
        __find_if(_RandomAccessIterator __first, _RandomAccessIterator __last,
    	      _Predicate __pred, random_access_iterator_tag)
        {
          typename iterator_traits<_RandomAccessIterator>::difference_type
    	__trip_count = (__last - __first) >> 2;
    
          for (; __trip_count > 0; --__trip_count)
    	{
    	  if (__pred(*__first))
    	    return __first;
    	  ++__first;
    
    	  if (__pred(*__first))
    	    return __first;
    	  ++__first;
    
    	  if (__pred(*__first))
    	    return __first;
    	  ++__first;
    
    	  if (__pred(*__first))
    	    return __first;
    	  ++__first;
    	}
    
          switch (__last - __first)
    	{
    	case 3:
    	  if (__pred(*__first))
    	    return __first;
    	  ++__first;
    	case 2:
    	  if (__pred(*__first))
    	    return __first;
    	  ++__first;
    	case 1:
    	  if (__pred(*__first))
    	    return __first;
    	  ++__first;
    	case 0:
    	default:
    	  return __last;
    	}
        }
    
      /// This is an overload used by find_if_not() for the Input Iterator case.
      template<typename _InputIterator, typename _Predicate>
        inline _InputIterator
        __find_if_not(_InputIterator __first, _InputIterator __last,
    		  _Predicate __pred, input_iterator_tag)
        {
          while (__first != __last && bool(__pred(*__first)))
    	++__first;
          return __first;
        }
    
      /// This is an overload used by find_if_not() for the RAI case.
      template<typename _RandomAccessIterator, typename _Predicate>
        _RandomAccessIterator
        __find_if_not(_RandomAccessIterator __first, _RandomAccessIterator __last,
    		  _Predicate __pred, random_access_iterator_tag)
        {
          typename iterator_traits<_RandomAccessIterator>::difference_type
    	__trip_count = (__last - __first) >> 2;
    
          for (; __trip_count > 0; --__trip_count)
    	{
    	  if (!bool(__pred(*__first)))
    	    return __first;
    	  ++__first;
    
    	  if (!bool(__pred(*__first)))
    	    return __first;
    	  ++__first;
    
    	  if (!bool(__pred(*__first)))
    	    return __first;
    	  ++__first;
    
    	  if (!bool(__pred(*__first)))
    	    return __first;
    	  ++__first;
    	}
    
          switch (__last - __first)
    	{
    	case 3:
    	  if (!bool(__pred(*__first)))
    	    return __first;
    	  ++__first;
    	case 2:
    	  if (!bool(__pred(*__first)))
    	    return __first;
    	  ++__first;
    	case 1:
    	  if (!bool(__pred(*__first)))
    	    return __first;
    	  ++__first;
    	case 0:
    	default:
    	  return __last;
    	}
        }
    
      /// Provided for stable_partition to use.
      template<typename _InputIterator, typename _Predicate>
        inline _InputIterator
        __find_if_not(_InputIterator __first, _InputIterator __last,
    		  _Predicate __pred)
        {
          return std::__find_if_not(__first, __last, __pred,
    				std::__iterator_category(__first));
        }
    
      /// Like find_if_not(), but uses and updates a count of the
      /// remaining range length instead of comparing against an end
      /// iterator.
      template<typename _InputIterator, typename _Predicate, typename _Distance>
        _InputIterator
        __find_if_not_n(_InputIterator __first, _Distance& __len, _Predicate __pred)
        {
          for (; __len; --__len, ++__first)
    	if (!bool(__pred(*__first)))
    	  break;
          return __first;
        }
    
      // set_difference
      // set_intersection
      // set_symmetric_difference
      // set_union
      // for_each
      // find
      // find_if
      // find_first_of
      // adjacent_find
      // count
      // count_if
      // search
    
      /**
       *  This is an uglified
       *  search_n(_ForwardIterator, _ForwardIterator, _Integer, const _Tp&)
       *  overloaded for forward iterators.
      */
      template<typename _ForwardIterator, typename _Integer, typename _Tp>
        _ForwardIterator
        __search_n(_ForwardIterator __first, _ForwardIterator __last,
    	       _Integer __count, const _Tp& __val,
    	       std::forward_iterator_tag)
        {
          __first = _GLIBCXX_STD_A::find(__first, __last, __val);
          while (__first != __last)
    	{
    	  typename iterator_traits<_ForwardIterator>::difference_type
    	    __n = __count;
    	  _ForwardIterator __i = __first;
    	  ++__i;
    	  while (__i != __last && __n != 1 && *__i == __val)
    	    {
    	      ++__i;
    	      --__n;
    	    }
    	  if (__n == 1)
    	    return __first;
    	  if (__i == __last)
    	    return __last;
    	  __first = _GLIBCXX_STD_A::find(++__i, __last, __val);
    	}
          return __last;
        }
    
      /**
       *  This is an uglified
       *  search_n(_ForwardIterator, _ForwardIterator, _Integer, const _Tp&)
       *  overloaded for random access iterators.
      */
      template<typename _RandomAccessIter, typename _Integer, typename _Tp>
        _RandomAccessIter
        __search_n(_RandomAccessIter __first, _RandomAccessIter __last,
    	       _Integer __count, const _Tp& __val, 
    	       std::random_access_iterator_tag)
        {
          
          typedef typename std::iterator_traits<_RandomAccessIter>::difference_type
    	_DistanceType;
    
          _DistanceType __tailSize = __last - __first;
          const _DistanceType __pattSize = __count;
    
          if (__tailSize < __pattSize)
            return __last;
    
          const _DistanceType __skipOffset = __pattSize - 1;
          _RandomAccessIter __lookAhead = __first + __skipOffset;
          __tailSize -= __pattSize;
    
          while (1) // the main loop...
    	{
    	  // __lookAhead here is always pointing to the last element of next 
    	  // possible match.
    	  while (!(*__lookAhead == __val)) // the skip loop...
    	    {
    	      if (__tailSize < __pattSize)
    		return __last;  // Failure
    	      __lookAhead += __pattSize;
    	      __tailSize -= __pattSize;
    	    }
    	  _DistanceType __remainder = __skipOffset;
    	  for (_RandomAccessIter __backTrack = __lookAhead - 1; 
    	       *__backTrack == __val; --__backTrack)
    	    {
    	      if (--__remainder == 0)
    		return (__lookAhead - __skipOffset); // Success
    	    }
    	  if (__remainder > __tailSize)
    	    return __last; // Failure
    	  __lookAhead += __remainder;
    	  __tailSize -= __remainder;
    	}
        }
    
      // search_n
    
      /**
       *  This is an uglified
       *  search_n(_ForwardIterator, _ForwardIterator, _Integer, const _Tp&,
       *	       _BinaryPredicate)
       *  overloaded for forward iterators.
      */
      template<typename _ForwardIterator, typename _Integer, typename _Tp,
               typename _BinaryPredicate>
        _ForwardIterator
        __search_n(_ForwardIterator __first, _ForwardIterator __last,
    	       _Integer __count, const _Tp& __val,
    	       _BinaryPredicate __binary_pred, std::forward_iterator_tag)
        {
          while (__first != __last && !bool(__binary_pred(*__first, __val)))
            ++__first;
    
          while (__first != __last)
    	{
    	  typename iterator_traits<_ForwardIterator>::difference_type
    	    __n = __count;
    	  _ForwardIterator __i = __first;
    	  ++__i;
    	  while (__i != __last && __n != 1 && bool(__binary_pred(*__i, __val)))
    	    {
    	      ++__i;
    	      --__n;
    	    }
    	  if (__n == 1)
    	    return __first;
    	  if (__i == __last)
    	    return __last;
    	  __first = ++__i;
    	  while (__first != __last
    		 && !bool(__binary_pred(*__first, __val)))
    	    ++__first;
    	}
          return __last;
        }
    
      /**
       *  This is an uglified
       *  search_n(_ForwardIterator, _ForwardIterator, _Integer, const _Tp&,
       *	       _BinaryPredicate)
       *  overloaded for random access iterators.
      */
      template<typename _RandomAccessIter, typename _Integer, typename _Tp,
    	   typename _BinaryPredicate>
        _RandomAccessIter
        __search_n(_RandomAccessIter __first, _RandomAccessIter __last,
    	       _Integer __count, const _Tp& __val,
    	       _BinaryPredicate __binary_pred, std::random_access_iterator_tag)
        {
          
          typedef typename std::iterator_traits<_RandomAccessIter>::difference_type
    	_DistanceType;
    
          _DistanceType __tailSize = __last - __first;
          const _DistanceType __pattSize = __count;
    
          if (__tailSize < __pattSize)
            return __last;
    
          const _DistanceType __skipOffset = __pattSize - 1;
          _RandomAccessIter __lookAhead = __first + __skipOffset;
          __tailSize -= __pattSize;
    
          while (1) // the main loop...
    	{
    	  // __lookAhead here is always pointing to the last element of next 
    	  // possible match.
    	  while (!bool(__binary_pred(*__lookAhead, __val))) // the skip loop...
    	    {
    	      if (__tailSize < __pattSize)
    		return __last;  // Failure
    	      __lookAhead += __pattSize;
    	      __tailSize -= __pattSize;
    	    }
    	  _DistanceType __remainder = __skipOffset;
    	  for (_RandomAccessIter __backTrack = __lookAhead - 1; 
    	       __binary_pred(*__backTrack, __val); --__backTrack)
    	    {
    	      if (--__remainder == 0)
    		return (__lookAhead - __skipOffset); // Success
    	    }
    	  if (__remainder > __tailSize)
    	    return __last; // Failure
    	  __lookAhead += __remainder;
    	  __tailSize -= __remainder;
    	}
        }
    
      // find_end for forward iterators.
      template<typename _ForwardIterator1, typename _ForwardIterator2>
        _ForwardIterator1
        __find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
    	       _ForwardIterator2 __first2, _ForwardIterator2 __last2,
    	       forward_iterator_tag, forward_iterator_tag)
        {
          if (__first2 == __last2)
    	return __last1;
          else
    	{
    	  _ForwardIterator1 __result = __last1;
    	  while (1)
    	    {
    	      _ForwardIterator1 __new_result
    		= _GLIBCXX_STD_A::search(__first1, __last1, __first2, __last2);
    	      if (__new_result == __last1)
    		return __result;
    	      else
    		{
    		  __result = __new_result;
    		  __first1 = __new_result;
    		  ++__first1;
    		}
    	    }
    	}
        }
    
      template<typename _ForwardIterator1, typename _ForwardIterator2,
    	   typename _BinaryPredicate>
        _ForwardIterator1
        __find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
    	       _ForwardIterator2 __first2, _ForwardIterator2 __last2,
    	       forward_iterator_tag, forward_iterator_tag,
    	       _BinaryPredicate __comp)
        {
          if (__first2 == __last2)
    	return __last1;
          else
    	{
    	  _ForwardIterator1 __result = __last1;
    	  while (1)
    	    {
    	      _ForwardIterator1 __new_result
    		= _GLIBCXX_STD_A::search(__first1, __last1, __first2,
    					 __last2, __comp);
    	      if (__new_result == __last1)
    		return __result;
    	      else
    		{
    		  __result = __new_result;
    		  __first1 = __new_result;
    		  ++__first1;
    		}
    	    }
    	}
        }
    
      // find_end for bidirectional iterators (much faster).
      template<typename _BidirectionalIterator1, typename _BidirectionalIterator2>
        _BidirectionalIterator1
        __find_end(_BidirectionalIterator1 __first1,
    	       _BidirectionalIterator1 __last1,
    	       _BidirectionalIterator2 __first2,
    	       _BidirectionalIterator2 __last2,
    	       bidirectional_iterator_tag, bidirectional_iterator_tag)
        {
          // concept requirements
          __glibcxx_function_requires(_BidirectionalIteratorConcept<
    				  _BidirectionalIterator1>)
          __glibcxx_function_requires(_BidirectionalIteratorConcept<
    				  _BidirectionalIterator2>)
    
          typedef reverse_iterator<_BidirectionalIterator1> _RevIterator1;
          typedef reverse_iterator<_BidirectionalIterator2> _RevIterator2;
    
          _RevIterator1 __rlast1(__first1);
          _RevIterator2 __rlast2(__first2);
          _RevIterator1 __rresult = _GLIBCXX_STD_A::search(_RevIterator1(__last1),
    						       __rlast1,
    						       _RevIterator2(__last2),
    						       __rlast2);
    
          if (__rresult == __rlast1)
    	return __last1;
          else
    	{
    	  _BidirectionalIterator1 __result = __rresult.base();
    	  std::advance(__result, -std::distance(__first2, __last2));
    	  return __result;
    	}
        }
    
      template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,
    	   typename _BinaryPredicate>
        _BidirectionalIterator1
        __find_end(_BidirectionalIterator1 __first1,
    	       _BidirectionalIterator1 __last1,
    	       _BidirectionalIterator2 __first2,
    	       _BidirectionalIterator2 __last2,
    	       bidirectional_iterator_tag, bidirectional_iterator_tag,
    	       _BinaryPredicate __comp)
        {
          // concept requirements
          __glibcxx_function_requires(_BidirectionalIteratorConcept<
    				  _BidirectionalIterator1>)
          __glibcxx_function_requires(_BidirectionalIteratorConcept<
    				  _BidirectionalIterator2>)
    
          typedef reverse_iterator<_BidirectionalIterator1> _RevIterator1;
          typedef reverse_iterator<_BidirectionalIterator2> _RevIterator2;
    
          _RevIterator1 __rlast1(__first1);
          _RevIterator2 __rlast2(__first2);
          _RevIterator1 __rresult = std::search(_RevIterator1(__last1), __rlast1,
    					    _RevIterator2(__last2), __rlast2,
    					    __comp);
    
          if (__rresult == __rlast1)
    	return __last1;
          else
    	{
    	  _BidirectionalIterator1 __result = __rresult.base();
    	  std::advance(__result, -std::distance(__first2, __last2));
    	  return __result;
    	}
        }
    
      /**
       *  @brief  Find last matching subsequence in a sequence.
       *  @ingroup non_mutating_algorithms
       *  @param  __first1  Start of range to search.
       *  @param  __last1   End of range to search.
       *  @param  __first2  Start of sequence to match.
       *  @param  __last2   End of sequence to match.
       *  @return   The last iterator @c i in the range
       *  @p [__first1,__last1-(__last2-__first2)) such that @c *(i+N) ==
       *  @p *(__first2+N) for each @c N in the range @p
       *  [0,__last2-__first2), or @p __last1 if no such iterator exists.
       *
       *  Searches the range @p [__first1,__last1) for a sub-sequence that
       *  compares equal value-by-value with the sequence given by @p
       *  [__first2,__last2) and returns an iterator to the __first
       *  element of the sub-sequence, or @p __last1 if the sub-sequence
       *  is not found.  The sub-sequence will be the last such
       *  subsequence contained in [__first,__last1).
       *
       *  Because the sub-sequence must lie completely within the range @p
       *  [__first1,__last1) it must start at a position less than @p
       *  __last1-(__last2-__first2) where @p __last2-__first2 is the
       *  length of the sub-sequence.  This means that the returned
       *  iterator @c i will be in the range @p
       *  [__first1,__last1-(__last2-__first2))
      */
      template<typename _ForwardIterator1, typename _ForwardIterator2>
        inline _ForwardIterator1
        find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
    	     _ForwardIterator2 __first2, _ForwardIterator2 __last2)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
          __glibcxx_function_requires(_EqualOpConcept<
    	    typename iterator_traits<_ForwardIterator1>::value_type,
    	    typename iterator_traits<_ForwardIterator2>::value_type>)
          __glibcxx_requires_valid_range(__first1, __last1);
          __glibcxx_requires_valid_range(__first2, __last2);
    
          return std::__find_end(__first1, __last1, __first2, __last2,
    			     std::__iterator_category(__first1),
    			     std::__iterator_category(__first2));
        }
    
      /**
       *  @brief  Find last matching subsequence in a sequence using a predicate.
       *  @ingroup non_mutating_algorithms
       *  @param  __first1  Start of range to search.
       *  @param  __last1   End of range to search.
       *  @param  __first2  Start of sequence to match.
       *  @param  __last2   End of sequence to match.
       *  @param  __comp    The predicate to use.
       *  @return The last iterator @c i in the range @p
       *  [__first1,__last1-(__last2-__first2)) such that @c
       *  predicate(*(i+N), @p (__first2+N)) is true for each @c N in the
       *  range @p [0,__last2-__first2), or @p __last1 if no such iterator
       *  exists.
       *
       *  Searches the range @p [__first1,__last1) for a sub-sequence that
       *  compares equal value-by-value with the sequence given by @p
       *  [__first2,__last2) using comp as a predicate and returns an
       *  iterator to the first element of the sub-sequence, or @p __last1
       *  if the sub-sequence is not found.  The sub-sequence will be the
       *  last such subsequence contained in [__first,__last1).
       *
       *  Because the sub-sequence must lie completely within the range @p
       *  [__first1,__last1) it must start at a position less than @p
       *  __last1-(__last2-__first2) where @p __last2-__first2 is the
       *  length of the sub-sequence.  This means that the returned
       *  iterator @c i will be in the range @p
       *  [__first1,__last1-(__last2-__first2))
      */
      template<typename _ForwardIterator1, typename _ForwardIterator2,
    	   typename _BinaryPredicate>
        inline _ForwardIterator1
        find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
    	     _ForwardIterator2 __first2, _ForwardIterator2 __last2,
    	     _BinaryPredicate __comp)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
    	    typename iterator_traits<_ForwardIterator1>::value_type,
    	    typename iterator_traits<_ForwardIterator2>::value_type>)
          __glibcxx_requires_valid_range(__first1, __last1);
          __glibcxx_requires_valid_range(__first2, __last2);
    
          return std::__find_end(__first1, __last1, __first2, __last2,
    			     std::__iterator_category(__first1),
    			     std::__iterator_category(__first2),
    			     __comp);
        }
    
    #ifdef __GXX_EXPERIMENTAL_CXX0X__
      /**
       *  @brief  Checks that a predicate is true for all the elements
       *          of a sequence.
       *  @ingroup non_mutating_algorithms
       *  @param  __first   An input iterator.
       *  @param  __last    An input iterator.
       *  @param  __pred    A predicate.
       *  @return  True if the check is true, false otherwise.
       *
       *  Returns true if @p __pred is true for each element in the range
       *  @p [__first,__last), and false otherwise.
      */
      template<typename _InputIterator, typename _Predicate>
        inline bool
        all_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
        { return __last == std::find_if_not(__first, __last, __pred); }
    
      /**
       *  @brief  Checks that a predicate is false for all the elements
       *          of a sequence.
       *  @ingroup non_mutating_algorithms
       *  @param  __first   An input iterator.
       *  @param  __last    An input iterator.
       *  @param  __pred    A predicate.
       *  @return  True if the check is true, false otherwise.
       *
       *  Returns true if @p __pred is false for each element in the range
       *  @p [__first,__last), and false otherwise.
      */
      template<typename _InputIterator, typename _Predicate>
        inline bool
        none_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
        { return __last == _GLIBCXX_STD_A::find_if(__first, __last, __pred); }
    
      /**
       *  @brief  Checks that a predicate is false for at least an element
       *          of a sequence.
       *  @ingroup non_mutating_algorithms
       *  @param  __first   An input iterator.
       *  @param  __last    An input iterator.
       *  @param  __pred    A predicate.
       *  @return  True if the check is true, false otherwise.
       *
       *  Returns true if an element exists in the range @p
       *  [__first,__last) such that @p __pred is true, and false
       *  otherwise.
      */
      template<typename _InputIterator, typename _Predicate>
        inline bool
        any_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
        { return !std::none_of(__first, __last, __pred); }
    
      /**
       *  @brief  Find the first element in a sequence for which a
       *          predicate is false.
       *  @ingroup non_mutating_algorithms
       *  @param  __first  An input iterator.
       *  @param  __last   An input iterator.
       *  @param  __pred   A predicate.
       *  @return   The first iterator @c i in the range @p [__first,__last)
       *  such that @p __pred(*i) is false, or @p __last if no such iterator exists.
      */
      template<typename _InputIterator, typename _Predicate>
        inline _InputIterator
        find_if_not(_InputIterator __first, _InputIterator __last,
    		_Predicate __pred)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    	      typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
          return std::__find_if_not(__first, __last, __pred);
        }
    
      /**
       *  @brief  Checks whether the sequence is partitioned.
       *  @ingroup mutating_algorithms
       *  @param  __first  An input iterator.
       *  @param  __last   An input iterator.
       *  @param  __pred   A predicate.
       *  @return  True if the range @p [__first,__last) is partioned by @p __pred,
       *  i.e. if all elements that satisfy @p __pred appear before those that
       *  do not.
      */
      template<typename _InputIterator, typename _Predicate>
        inline bool
        is_partitioned(_InputIterator __first, _InputIterator __last,
    		   _Predicate __pred)
        {
          __first = std::find_if_not(__first, __last, __pred);
          return std::none_of(__first, __last, __pred);
        }
    
      /**
       *  @brief  Find the partition point of a partitioned range.
       *  @ingroup mutating_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __pred    A predicate.
       *  @return  An iterator @p mid such that @p all_of(__first, mid, __pred)
       *           and @p none_of(mid, __last, __pred) are both true.
      */
      template<typename _ForwardIterator, typename _Predicate>
        _ForwardIterator
        partition_point(_ForwardIterator __first, _ForwardIterator __last,
    		    _Predicate __pred)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    	      typename iterator_traits<_ForwardIterator>::value_type>)
    
          // A specific debug-mode test will be necessary...
          __glibcxx_requires_valid_range(__first, __last);
    
          typedef typename iterator_traits<_ForwardIterator>::difference_type
    	_DistanceType;
    
          _DistanceType __len = std::distance(__first, __last);
          _DistanceType __half;
          _ForwardIterator __middle;
    
          while (__len > 0)
    	{
    	  __half = __len >> 1;
    	  __middle = __first;
    	  std::advance(__middle, __half);
    	  if (__pred(*__middle))
    	    {
    	      __first = __middle;
    	      ++__first;
    	      __len = __len - __half - 1;
    	    }
    	  else
    	    __len = __half;
    	}
          return __first;
        }
    #endif
    
    
      /**
       *  @brief Copy a sequence, removing elements of a given value.
       *  @ingroup mutating_algorithms
       *  @param  __first   An input iterator.
       *  @param  __last    An input iterator.
       *  @param  __result  An output iterator.
       *  @param  __value   The value to be removed.
       *  @return   An iterator designating the end of the resulting sequence.
       *
       *  Copies each element in the range @p [__first,__last) not equal
       *  to @p __value to the range beginning at @p __result.
       *  remove_copy() is stable, so the relative order of elements that
       *  are copied is unchanged.
      */
      template<typename _InputIterator, typename _OutputIterator, typename _Tp>
        _OutputIterator
        remove_copy(_InputIterator __first, _InputIterator __last,
    		_OutputIterator __result, const _Tp& __value)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_function_requires(_EqualOpConcept<
    	    typename iterator_traits<_InputIterator>::value_type, _Tp>)
          __glibcxx_requires_valid_range(__first, __last);
    
          for (; __first != __last; ++__first)
    	if (!(*__first == __value))
    	  {
    	    *__result = *__first;
    	    ++__result;
    	  }
          return __result;
        }
    
      /**
       *  @brief Copy a sequence, removing elements for which a predicate is true.
       *  @ingroup mutating_algorithms
       *  @param  __first   An input iterator.
       *  @param  __last    An input iterator.
       *  @param  __result  An output iterator.
       *  @param  __pred    A predicate.
       *  @return   An iterator designating the end of the resulting sequence.
       *
       *  Copies each element in the range @p [__first,__last) for which
       *  @p __pred returns false to the range beginning at @p __result.
       *
       *  remove_copy_if() is stable, so the relative order of elements that are
       *  copied is unchanged.
      */
      template<typename _InputIterator, typename _OutputIterator,
    	   typename _Predicate>
        _OutputIterator
        remove_copy_if(_InputIterator __first, _InputIterator __last,
    		   _OutputIterator __result, _Predicate __pred)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          for (; __first != __last; ++__first)
    	if (!bool(__pred(*__first)))
    	  {
    	    *__result = *__first;
    	    ++__result;
    	  }
          return __result;
        }
    
    #ifdef __GXX_EXPERIMENTAL_CXX0X__
      /**
       *  @brief Copy the elements of a sequence for which a predicate is true.
       *  @ingroup mutating_algorithms
       *  @param  __first   An input iterator.
       *  @param  __last    An input iterator.
       *  @param  __result  An output iterator.
       *  @param  __pred    A predicate.
       *  @return   An iterator designating the end of the resulting sequence.
       *
       *  Copies each element in the range @p [__first,__last) for which
       *  @p __pred returns true to the range beginning at @p __result.
       *
       *  copy_if() is stable, so the relative order of elements that are
       *  copied is unchanged.
      */
      template<typename _InputIterator, typename _OutputIterator,
    	   typename _Predicate>
        _OutputIterator
        copy_if(_InputIterator __first, _InputIterator __last,
    	    _OutputIterator __result, _Predicate __pred)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          for (; __first != __last; ++__first)
    	if (__pred(*__first))
    	  {
    	    *__result = *__first;
    	    ++__result;
    	  }
          return __result;
        }
    
    
      template<typename _InputIterator, typename _Size, typename _OutputIterator>
        _OutputIterator
        __copy_n(_InputIterator __first, _Size __n,
    	     _OutputIterator __result, input_iterator_tag)
        {
          if (__n > 0)
    	{
    	  while (true)
    	    {
    	      *__result = *__first;
    	      ++__result;
    	      if (--__n > 0)
    		++__first;
    	      else
    		break;
    	    }
    	}
          return __result;
        }
    
      template<typename _RandomAccessIterator, typename _Size,
    	   typename _OutputIterator>
        inline _OutputIterator
        __copy_n(_RandomAccessIterator __first, _Size __n,
    	     _OutputIterator __result, random_access_iterator_tag)
        { return std::copy(__first, __first + __n, __result); }
    
      /**
       *  @brief Copies the range [first,first+n) into [result,result+n).
       *  @ingroup mutating_algorithms
       *  @param  __first  An input iterator.
       *  @param  __n      The number of elements to copy.
       *  @param  __result An output iterator.
       *  @return  result+n.
       *
       *  This inline function will boil down to a call to @c memmove whenever
       *  possible.  Failing that, if random access iterators are passed, then the
       *  loop count will be known (and therefore a candidate for compiler
       *  optimizations such as unrolling).
      */
      template<typename _InputIterator, typename _Size, typename _OutputIterator>
        inline _OutputIterator
        copy_n(_InputIterator __first, _Size __n, _OutputIterator __result)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    	    typename iterator_traits<_InputIterator>::value_type>)
    
          return std::__copy_n(__first, __n, __result,
    			   std::__iterator_category(__first));
        }
    
      /**
       *  @brief Copy the elements of a sequence to separate output sequences
       *         depending on the truth value of a predicate.
       *  @ingroup mutating_algorithms
       *  @param  __first   An input iterator.
       *  @param  __last    An input iterator.
       *  @param  __out_true   An output iterator.
       *  @param  __out_false  An output iterator.
       *  @param  __pred    A predicate.
       *  @return   A pair designating the ends of the resulting sequences.
       *
       *  Copies each element in the range @p [__first,__last) for which
       *  @p __pred returns true to the range beginning at @p out_true
       *  and each element for which @p __pred returns false to @p __out_false.
      */
      template<typename _InputIterator, typename _OutputIterator1,
    	   typename _OutputIterator2, typename _Predicate>
        pair<_OutputIterator1, _OutputIterator2>
        partition_copy(_InputIterator __first, _InputIterator __last,
    		   _OutputIterator1 __out_true, _OutputIterator2 __out_false,
    		   _Predicate __pred)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator1,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator2,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
          
          for (; __first != __last; ++__first)
    	if (__pred(*__first))
    	  {
    	    *__out_true = *__first;
    	    ++__out_true;
    	  }
    	else
    	  {
    	    *__out_false = *__first;
    	    ++__out_false;
    	  }
    
          return pair<_OutputIterator1, _OutputIterator2>(__out_true, __out_false);
        }
    #endif
    
      /**
       *  @brief Remove elements from a sequence.
       *  @ingroup mutating_algorithms
       *  @param  __first  An input iterator.
       *  @param  __last   An input iterator.
       *  @param  __value  The value to be removed.
       *  @return   An iterator designating the end of the resulting sequence.
       *
       *  All elements equal to @p __value are removed from the range
       *  @p [__first,__last).
       *
       *  remove() is stable, so the relative order of elements that are
       *  not removed is unchanged.
       *
       *  Elements between the end of the resulting sequence and @p __last
       *  are still present, but their value is unspecified.
      */
      template<typename _ForwardIterator, typename _Tp>
        _ForwardIterator
        remove(_ForwardIterator __first, _ForwardIterator __last,
    	   const _Tp& __value)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
    				  _ForwardIterator>)
          __glibcxx_function_requires(_EqualOpConcept<
    	    typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
          __glibcxx_requires_valid_range(__first, __last);
    
          __first = _GLIBCXX_STD_A::find(__first, __last, __value);
          if(__first == __last)
            return __first;
          _ForwardIterator __result = __first;
          ++__first;
          for(; __first != __last; ++__first)
            if(!(*__first == __value))
              {
                *__result = _GLIBCXX_MOVE(*__first);
                ++__result;
              }
          return __result;
        }
    
      /**
       *  @brief Remove elements from a sequence using a predicate.
       *  @ingroup mutating_algorithms
       *  @param  __first  A forward iterator.
       *  @param  __last   A forward iterator.
       *  @param  __pred   A predicate.
       *  @return   An iterator designating the end of the resulting sequence.
       *
       *  All elements for which @p __pred returns true are removed from the range
       *  @p [__first,__last).
       *
       *  remove_if() is stable, so the relative order of elements that are
       *  not removed is unchanged.
       *
       *  Elements between the end of the resulting sequence and @p __last
       *  are still present, but their value is unspecified.
      */
      template<typename _ForwardIterator, typename _Predicate>
        _ForwardIterator
        remove_if(_ForwardIterator __first, _ForwardIterator __last,
    	      _Predicate __pred)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
    				  _ForwardIterator>)
          __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          __first = _GLIBCXX_STD_A::find_if(__first, __last, __pred);
          if(__first == __last)
            return __first;
          _ForwardIterator __result = __first;
          ++__first;
          for(; __first != __last; ++__first)
            if(!bool(__pred(*__first)))
              {
                *__result = _GLIBCXX_MOVE(*__first);
                ++__result;
              }
          return __result;
        }
    
      /**
       *  @brief Remove consecutive duplicate values from a sequence.
       *  @ingroup mutating_algorithms
       *  @param  __first  A forward iterator.
       *  @param  __last   A forward iterator.
       *  @return  An iterator designating the end of the resulting sequence.
       *
       *  Removes all but the first element from each group of consecutive
       *  values that compare equal.
       *  unique() is stable, so the relative order of elements that are
       *  not removed is unchanged.
       *  Elements between the end of the resulting sequence and @p __last
       *  are still present, but their value is unspecified.
      */
      template<typename _ForwardIterator>
        _ForwardIterator
        unique(_ForwardIterator __first, _ForwardIterator __last)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
    				  _ForwardIterator>)
          __glibcxx_function_requires(_EqualityComparableConcept<
    		     typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          // Skip the beginning, if already unique.
          __first = _GLIBCXX_STD_A::adjacent_find(__first, __last);
          if (__first == __last)
    	return __last;
    
          // Do the real copy work.
          _ForwardIterator __dest = __first;
          ++__first;
          while (++__first != __last)
    	if (!(*__dest == *__first))
    	  *++__dest = _GLIBCXX_MOVE(*__first);
          return ++__dest;
        }
    
      /**
       *  @brief Remove consecutive values from a sequence using a predicate.
       *  @ingroup mutating_algorithms
       *  @param  __first        A forward iterator.
       *  @param  __last         A forward iterator.
       *  @param  __binary_pred  A binary predicate.
       *  @return  An iterator designating the end of the resulting sequence.
       *
       *  Removes all but the first element from each group of consecutive
       *  values for which @p __binary_pred returns true.
       *  unique() is stable, so the relative order of elements that are
       *  not removed is unchanged.
       *  Elements between the end of the resulting sequence and @p __last
       *  are still present, but their value is unspecified.
      */
      template<typename _ForwardIterator, typename _BinaryPredicate>
        _ForwardIterator
        unique(_ForwardIterator __first, _ForwardIterator __last,
               _BinaryPredicate __binary_pred)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
    				  _ForwardIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
    		typename iterator_traits<_ForwardIterator>::value_type,
    		typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          // Skip the beginning, if already unique.
          __first = _GLIBCXX_STD_A::adjacent_find(__first, __last, __binary_pred);
          if (__first == __last)
    	return __last;
    
          // Do the real copy work.
          _ForwardIterator __dest = __first;
          ++__first;
          while (++__first != __last)
    	if (!bool(__binary_pred(*__dest, *__first)))
    	  *++__dest = _GLIBCXX_MOVE(*__first);
          return ++__dest;
        }
    
      /**
       *  This is an uglified unique_copy(_InputIterator, _InputIterator,
       *                                  _OutputIterator)
       *  overloaded for forward iterators and output iterator as result.
      */
      template<typename _ForwardIterator, typename _OutputIterator>
        _OutputIterator
        __unique_copy(_ForwardIterator __first, _ForwardIterator __last,
    		  _OutputIterator __result,
    		  forward_iterator_tag, output_iterator_tag)
        {
          // concept requirements -- taken care of in dispatching function
          _ForwardIterator __next = __first;
          *__result = *__first;
          while (++__next != __last)
    	if (!(*__first == *__next))
    	  {
    	    __first = __next;
    	    *++__result = *__first;
    	  }
          return ++__result;
        }
    
      /**
       *  This is an uglified unique_copy(_InputIterator, _InputIterator,
       *                                  _OutputIterator)
       *  overloaded for input iterators and output iterator as result.
      */
      template<typename _InputIterator, typename _OutputIterator>
        _OutputIterator
        __unique_copy(_InputIterator __first, _InputIterator __last,
    		  _OutputIterator __result,
    		  input_iterator_tag, output_iterator_tag)
        {
          // concept requirements -- taken care of in dispatching function
          typename iterator_traits<_InputIterator>::value_type __value = *__first;
          *__result = __value;
          while (++__first != __last)
    	if (!(__value == *__first))
    	  {
    	    __value = *__first;
    	    *++__result = __value;
    	  }
          return ++__result;
        }
    
      /**
       *  This is an uglified unique_copy(_InputIterator, _InputIterator,
       *                                  _OutputIterator)
       *  overloaded for input iterators and forward iterator as result.
      */
      template<typename _InputIterator, typename _ForwardIterator>
        _ForwardIterator
        __unique_copy(_InputIterator __first, _InputIterator __last,
    		  _ForwardIterator __result,
    		  input_iterator_tag, forward_iterator_tag)
        {
          // concept requirements -- taken care of in dispatching function
          *__result = *__first;
          while (++__first != __last)
    	if (!(*__result == *__first))
    	  *++__result = *__first;
          return ++__result;
        }
    
      /**
       *  This is an uglified
       *  unique_copy(_InputIterator, _InputIterator, _OutputIterator,
       *              _BinaryPredicate)
       *  overloaded for forward iterators and output iterator as result.
      */
      template<typename _ForwardIterator, typename _OutputIterator,
    	   typename _BinaryPredicate>
        _OutputIterator
        __unique_copy(_ForwardIterator __first, _ForwardIterator __last,
    		  _OutputIterator __result, _BinaryPredicate __binary_pred,
    		  forward_iterator_tag, output_iterator_tag)
        {
          // concept requirements -- iterators already checked
          __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
    	  typename iterator_traits<_ForwardIterator>::value_type,
    	  typename iterator_traits<_ForwardIterator>::value_type>)
    
          _ForwardIterator __next = __first;
          *__result = *__first;
          while (++__next != __last)
    	if (!bool(__binary_pred(*__first, *__next)))
    	  {
    	    __first = __next;
    	    *++__result = *__first;
    	  }
          return ++__result;
        }
    
      /**
       *  This is an uglified
       *  unique_copy(_InputIterator, _InputIterator, _OutputIterator,
       *              _BinaryPredicate)
       *  overloaded for input iterators and output iterator as result.
      */
      template<typename _InputIterator, typename _OutputIterator,
    	   typename _BinaryPredicate>
        _OutputIterator
        __unique_copy(_InputIterator __first, _InputIterator __last,
    		  _OutputIterator __result, _BinaryPredicate __binary_pred,
    		  input_iterator_tag, output_iterator_tag)
        {
          // concept requirements -- iterators already checked
          __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
    	  typename iterator_traits<_InputIterator>::value_type,
    	  typename iterator_traits<_InputIterator>::value_type>)
    
          typename iterator_traits<_InputIterator>::value_type __value = *__first;
          *__result = __value;
          while (++__first != __last)
    	if (!bool(__binary_pred(__value, *__first)))
    	  {
    	    __value = *__first;
    	    *++__result = __value;
    	  }
          return ++__result;
        }
    
      /**
       *  This is an uglified
       *  unique_copy(_InputIterator, _InputIterator, _OutputIterator,
       *              _BinaryPredicate)
       *  overloaded for input iterators and forward iterator as result.
      */
      template<typename _InputIterator, typename _ForwardIterator,
    	   typename _BinaryPredicate>
        _ForwardIterator
        __unique_copy(_InputIterator __first, _InputIterator __last,
    		  _ForwardIterator __result, _BinaryPredicate __binary_pred,
    		  input_iterator_tag, forward_iterator_tag)
        {
          // concept requirements -- iterators already checked
          __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
    	  typename iterator_traits<_ForwardIterator>::value_type,
    	  typename iterator_traits<_InputIterator>::value_type>)
    
          *__result = *__first;
          while (++__first != __last)
    	if (!bool(__binary_pred(*__result, *__first)))
    	  *++__result = *__first;
          return ++__result;
        }
    
      /**
       *  This is an uglified reverse(_BidirectionalIterator,
       *                              _BidirectionalIterator)
       *  overloaded for bidirectional iterators.
      */
      template<typename _BidirectionalIterator>
        void
        __reverse(_BidirectionalIterator __first, _BidirectionalIterator __last,
    	      bidirectional_iterator_tag)
        {
          while (true)
    	if (__first == __last || __first == --__last)
    	  return;
    	else
    	  {
    	    std::iter_swap(__first, __last);
    	    ++__first;
    	  }
        }
    
      /**
       *  This is an uglified reverse(_BidirectionalIterator,
       *                              _BidirectionalIterator)
       *  overloaded for random access iterators.
      */
      template<typename _RandomAccessIterator>
        void
        __reverse(_RandomAccessIterator __first, _RandomAccessIterator __last,
    	      random_access_iterator_tag)
        {
          if (__first == __last)
    	return;
          --__last;
          while (__first < __last)
    	{
    	  std::iter_swap(__first, __last);
    	  ++__first;
    	  --__last;
    	}
        }
    
      /**
       *  @brief Reverse a sequence.
       *  @ingroup mutating_algorithms
       *  @param  __first  A bidirectional iterator.
       *  @param  __last   A bidirectional iterator.
       *  @return   reverse() returns no value.
       *
       *  Reverses the order of the elements in the range @p [__first,__last),
       *  so that the first element becomes the last etc.
       *  For every @c i such that @p 0<=i<=(__last-__first)/2), @p reverse()
       *  swaps @p *(__first+i) and @p *(__last-(i+1))
      */
      template<typename _BidirectionalIterator>
        inline void
        reverse(_BidirectionalIterator __first, _BidirectionalIterator __last)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
    				  _BidirectionalIterator>)
          __glibcxx_requires_valid_range(__first, __last);
          std::__reverse(__first, __last, std::__iterator_category(__first));
        }
    
      /**
       *  @brief Copy a sequence, reversing its elements.
       *  @ingroup mutating_algorithms
       *  @param  __first   A bidirectional iterator.
       *  @param  __last    A bidirectional iterator.
       *  @param  __result  An output iterator.
       *  @return  An iterator designating the end of the resulting sequence.
       *
       *  Copies the elements in the range @p [__first,__last) to the
       *  range @p [__result,__result+(__last-__first)) such that the
       *  order of the elements is reversed.  For every @c i such that @p
       *  0<=i<=(__last-__first), @p reverse_copy() performs the
       *  assignment @p *(__result+(__last-__first)-i) = *(__first+i).
       *  The ranges @p [__first,__last) and @p
       *  [__result,__result+(__last-__first)) must not overlap.
      */
      template<typename _BidirectionalIterator, typename _OutputIterator>
        _OutputIterator
        reverse_copy(_BidirectionalIterator __first, _BidirectionalIterator __last,
    		 _OutputIterator __result)
        {
          // concept requirements
          __glibcxx_function_requires(_BidirectionalIteratorConcept<
    				  _BidirectionalIterator>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    		typename iterator_traits<_BidirectionalIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          while (__first != __last)
    	{
    	  --__last;
    	  *__result = *__last;
    	  ++__result;
    	}
          return __result;
        }
    
      /**
       *  This is a helper function for the rotate algorithm specialized on RAIs.
       *  It returns the greatest common divisor of two integer values.
      */
      template<typename _EuclideanRingElement>
        _EuclideanRingElement
        __gcd(_EuclideanRingElement __m, _EuclideanRingElement __n)
        {
          while (__n != 0)
    	{
    	  _EuclideanRingElement __t = __m % __n;
    	  __m = __n;
    	  __n = __t;
    	}
          return __m;
        }
    
      /// This is a helper function for the rotate algorithm.
      template<typename _ForwardIterator>
        void
        __rotate(_ForwardIterator __first,
    	     _ForwardIterator __middle,
    	     _ForwardIterator __last,
    	     forward_iterator_tag)
        {
          if (__first == __middle || __last  == __middle)
    	return;
    
          _ForwardIterator __first2 = __middle;
          do
    	{
    	  std::iter_swap(__first, __first2);
    	  ++__first;
    	  ++__first2;
    	  if (__first == __middle)
    	    __middle = __first2;
    	}
          while (__first2 != __last);
    
          __first2 = __middle;
    
          while (__first2 != __last)
    	{
    	  std::iter_swap(__first, __first2);
    	  ++__first;
    	  ++__first2;
    	  if (__first == __middle)
    	    __middle = __first2;
    	  else if (__first2 == __last)
    	    __first2 = __middle;
    	}
        }
    
       /// This is a helper function for the rotate algorithm.
      template<typename _BidirectionalIterator>
        void
        __rotate(_BidirectionalIterator __first,
    	     _BidirectionalIterator __middle,
    	     _BidirectionalIterator __last,
    	      bidirectional_iterator_tag)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
    				  _BidirectionalIterator>)
    
          if (__first == __middle || __last  == __middle)
    	return;
    
          std::__reverse(__first,  __middle, bidirectional_iterator_tag());
          std::__reverse(__middle, __last,   bidirectional_iterator_tag());
    
          while (__first != __middle && __middle != __last)
    	{
    	  std::iter_swap(__first, --__last);
    	  ++__first;
    	}
    
          if (__first == __middle)
    	std::__reverse(__middle, __last,   bidirectional_iterator_tag());
          else
    	std::__reverse(__first,  __middle, bidirectional_iterator_tag());
        }
    
      /// This is a helper function for the rotate algorithm.
      template<typename _RandomAccessIterator>
        void
        __rotate(_RandomAccessIterator __first,
    	     _RandomAccessIterator __middle,
    	     _RandomAccessIterator __last,
    	     random_access_iterator_tag)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    				  _RandomAccessIterator>)
    
          if (__first == __middle || __last  == __middle)
    	return;
    
          typedef typename iterator_traits<_RandomAccessIterator>::difference_type
    	_Distance;
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
    
          _Distance __n = __last   - __first;
          _Distance __k = __middle - __first;
    
          if (__k == __n - __k)
    	{
    	  std::swap_ranges(__first, __middle, __middle);
    	  return;
    	}
    
          _RandomAccessIterator __p = __first;
    
          for (;;)
    	{
    	  if (__k < __n - __k)
    	    {
    	      if (__is_pod(_ValueType) && __k == 1)
    		{
    		  _ValueType __t = _GLIBCXX_MOVE(*__p);
    		  _GLIBCXX_MOVE3(__p + 1, __p + __n, __p);
    		  *(__p + __n - 1) = _GLIBCXX_MOVE(__t);
    		  return;
    		}
    	      _RandomAccessIterator __q = __p + __k;
    	      for (_Distance __i = 0; __i < __n - __k; ++ __i)
    		{
    		  std::iter_swap(__p, __q);
    		  ++__p;
    		  ++__q;
    		}
    	      __n %= __k;
    	      if (__n == 0)
    		return;
    	      std::swap(__n, __k);
    	      __k = __n - __k;
    	    }
    	  else
    	    {
    	      __k = __n - __k;
    	      if (__is_pod(_ValueType) && __k == 1)
    		{
    		  _ValueType __t = _GLIBCXX_MOVE(*(__p + __n - 1));
    		  _GLIBCXX_MOVE_BACKWARD3(__p, __p + __n - 1, __p + __n);
    		  *__p = _GLIBCXX_MOVE(__t);
    		  return;
    		}
    	      _RandomAccessIterator __q = __p + __n;
    	      __p = __q - __k;
    	      for (_Distance __i = 0; __i < __n - __k; ++ __i)
    		{
    		  --__p;
    		  --__q;
    		  std::iter_swap(__p, __q);
    		}
    	      __n %= __k;
    	      if (__n == 0)
    		return;
    	      std::swap(__n, __k);
    	    }
    	}
        }
    
      /**
       *  @brief Rotate the elements of a sequence.
       *  @ingroup mutating_algorithms
       *  @param  __first   A forward iterator.
       *  @param  __middle  A forward iterator.
       *  @param  __last    A forward iterator.
       *  @return  Nothing.
       *
       *  Rotates the elements of the range @p [__first,__last) by 
       *  @p (__middle - __first) positions so that the element at @p __middle
       *  is moved to @p __first, the element at @p __middle+1 is moved to
       *  @p __first+1 and so on for each element in the range
       *  @p [__first,__last).
       *
       *  This effectively swaps the ranges @p [__first,__middle) and
       *  @p [__middle,__last).
       *
       *  Performs
       *   @p *(__first+(n+(__last-__middle))%(__last-__first))=*(__first+n)
       *  for each @p n in the range @p [0,__last-__first).
      */
      template<typename _ForwardIterator>
        inline void
        rotate(_ForwardIterator __first, _ForwardIterator __middle,
    	   _ForwardIterator __last)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
    				  _ForwardIterator>)
          __glibcxx_requires_valid_range(__first, __middle);
          __glibcxx_requires_valid_range(__middle, __last);
    
          typedef typename iterator_traits<_ForwardIterator>::iterator_category
    	_IterType;
          std::__rotate(__first, __middle, __last, _IterType());
        }
    
      /**
       *  @brief Copy a sequence, rotating its elements.
       *  @ingroup mutating_algorithms
       *  @param  __first   A forward iterator.
       *  @param  __middle  A forward iterator.
       *  @param  __last    A forward iterator.
       *  @param  __result  An output iterator.
       *  @return   An iterator designating the end of the resulting sequence.
       *
       *  Copies the elements of the range @p [__first,__last) to the
       *  range beginning at @result, rotating the copied elements by 
       *  @p (__middle-__first) positions so that the element at @p __middle
       *  is moved to @p __result, the element at @p __middle+1 is moved
       *  to @p __result+1 and so on for each element in the range @p
       *  [__first,__last).
       *
       *  Performs 
       *  @p *(__result+(n+(__last-__middle))%(__last-__first))=*(__first+n)
       *  for each @p n in the range @p [0,__last-__first).
      */
      template<typename _ForwardIterator, typename _OutputIterator>
        _OutputIterator
        rotate_copy(_ForwardIterator __first, _ForwardIterator __middle,
                    _ForwardIterator __last, _OutputIterator __result)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    		typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __middle);
          __glibcxx_requires_valid_range(__middle, __last);
    
          return std::copy(__first, __middle,
                           std::copy(__middle, __last, __result));
        }
    
      /// This is a helper function...
      template<typename _ForwardIterator, typename _Predicate>
        _ForwardIterator
        __partition(_ForwardIterator __first, _ForwardIterator __last,
    		_Predicate __pred, forward_iterator_tag)
        {
          if (__first == __last)
    	return __first;
    
          while (__pred(*__first))
    	if (++__first == __last)
    	  return __first;
    
          _ForwardIterator __next = __first;
    
          while (++__next != __last)
    	if (__pred(*__next))
    	  {
    	    std::iter_swap(__first, __next);
    	    ++__first;
    	  }
    
          return __first;
        }
    
      /// This is a helper function...
      template<typename _BidirectionalIterator, typename _Predicate>
        _BidirectionalIterator
        __partition(_BidirectionalIterator __first, _BidirectionalIterator __last,
    		_Predicate __pred, bidirectional_iterator_tag)
        {
          while (true)
    	{
    	  while (true)
    	    if (__first == __last)
    	      return __first;
    	    else if (__pred(*__first))
    	      ++__first;
    	    else
    	      break;
    	  --__last;
    	  while (true)
    	    if (__first == __last)
    	      return __first;
    	    else if (!bool(__pred(*__last)))
    	      --__last;
    	    else
    	      break;
    	  std::iter_swap(__first, __last);
    	  ++__first;
    	}
        }
    
      // partition
    
      /// This is a helper function...
      /// Requires __len != 0 and !__pred(*__first),
      /// same as __stable_partition_adaptive.
      template<typename _ForwardIterator, typename _Predicate, typename _Distance>
        _ForwardIterator
        __inplace_stable_partition(_ForwardIterator __first,
    			       _Predicate __pred, _Distance __len)
        {
          if (__len == 1)
    	return __first;
          _ForwardIterator __middle = __first;
          std::advance(__middle, __len / 2);
          _ForwardIterator __left_split =
    	std::__inplace_stable_partition(__first, __pred, __len / 2);
          // Advance past true-predicate values to satisfy this
          // function's preconditions.
          _Distance __right_len = __len - __len / 2;
          _ForwardIterator __right_split =
    	std::__find_if_not_n(__middle, __right_len, __pred);
          if (__right_len)
    	__right_split = std::__inplace_stable_partition(__middle,
    							__pred,
    							__right_len);
          std::rotate(__left_split, __middle, __right_split);
          std::advance(__left_split, std::distance(__middle, __right_split));
          return __left_split;
        }
    
      /// This is a helper function...
      /// Requires __first != __last and !__pred(*__first)
      /// and __len == distance(__first, __last).
      ///
      /// !__pred(*__first) allows us to guarantee that we don't
      /// move-assign an element onto itself.
      template<typename _ForwardIterator, typename _Pointer, typename _Predicate,
    	   typename _Distance>
        _ForwardIterator
        __stable_partition_adaptive(_ForwardIterator __first,
    				_ForwardIterator __last,
    				_Predicate __pred, _Distance __len,
    				_Pointer __buffer,
    				_Distance __buffer_size)
        {
          if (__len <= __buffer_size)
    	{
    	  _ForwardIterator __result1 = __first;
    	  _Pointer __result2 = __buffer;
    	  // The precondition guarantees that !__pred(*__first), so
    	  // move that element to the buffer before starting the loop.
    	  // This ensures that we only call __pred once per element.
    	  *__result2 = _GLIBCXX_MOVE(*__first);
    	  ++__result2;
    	  ++__first;
    	  for (; __first != __last; ++__first)
    	    if (__pred(*__first))
    	      {
    		*__result1 = _GLIBCXX_MOVE(*__first);
    		++__result1;
    	      }
    	    else
    	      {
    		*__result2 = _GLIBCXX_MOVE(*__first);
    		++__result2;
    	      }
    	  _GLIBCXX_MOVE3(__buffer, __result2, __result1);
    	  return __result1;
    	}
          else
    	{
    	  _ForwardIterator __middle = __first;
    	  std::advance(__middle, __len / 2);
    	  _ForwardIterator __left_split =
    	    std::__stable_partition_adaptive(__first, __middle, __pred,
    					     __len / 2, __buffer,
    					     __buffer_size);
    	  // Advance past true-predicate values to satisfy this
    	  // function's preconditions.
    	  _Distance __right_len = __len - __len / 2;
    	  _ForwardIterator __right_split =
    	    std::__find_if_not_n(__middle, __right_len, __pred);
    	  if (__right_len)
    	    __right_split =
    	      std::__stable_partition_adaptive(__right_split, __last, __pred,
    					       __right_len,
    					       __buffer, __buffer_size);
    	  std::rotate(__left_split, __middle, __right_split);
    	  std::advance(__left_split, std::distance(__middle, __right_split));
    	  return __left_split;
    	}
        }
    
      /**
       *  @brief Move elements for which a predicate is true to the beginning
       *         of a sequence, preserving relative ordering.
       *  @ingroup mutating_algorithms
       *  @param  __first   A forward iterator.
       *  @param  __last    A forward iterator.
       *  @param  __pred    A predicate functor.
       *  @return  An iterator @p middle such that @p __pred(i) is true for each
       *  iterator @p i in the range @p [first,middle) and false for each @p i
       *  in the range @p [middle,last).
       *
       *  Performs the same function as @p partition() with the additional
       *  guarantee that the relative ordering of elements in each group is
       *  preserved, so any two elements @p x and @p y in the range
       *  @p [__first,__last) such that @p __pred(x)==__pred(y) will have the same
       *  relative ordering after calling @p stable_partition().
      */
      template<typename _ForwardIterator, typename _Predicate>
        _ForwardIterator
        stable_partition(_ForwardIterator __first, _ForwardIterator __last,
    		     _Predicate __pred)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
    				  _ForwardIterator>)
          __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          __first = std::__find_if_not(__first, __last, __pred);
    
          if (__first == __last)
    	return __first;
          else
    	{
    	  typedef typename iterator_traits<_ForwardIterator>::value_type
    	    _ValueType;
    	  typedef typename iterator_traits<_ForwardIterator>::difference_type
    	    _DistanceType;
    
    	  _Temporary_buffer<_ForwardIterator, _ValueType> __buf(__first,
    								__last);
    	if (__buf.size() > 0)
    	  return
    	    std::__stable_partition_adaptive(__first, __last, __pred,
    					  _DistanceType(__buf.requested_size()),
    					  __buf.begin(),
    					  _DistanceType(__buf.size()));
    	else
    	  return
    	    std::__inplace_stable_partition(__first, __pred,
    					 _DistanceType(__buf.requested_size()));
    	}
        }
    
      /// This is a helper function for the sort routines.
      template<typename _RandomAccessIterator>
        void
        __heap_select(_RandomAccessIterator __first,
    		  _RandomAccessIterator __middle,
    		  _RandomAccessIterator __last)
        {
          std::make_heap(__first, __middle);
          for (_RandomAccessIterator __i = __middle; __i < __last; ++__i)
    	if (*__i < *__first)
    	  std::__pop_heap(__first, __middle, __i);
        }
    
      /// This is a helper function for the sort routines.
      template<typename _RandomAccessIterator, typename _Compare>
        void
        __heap_select(_RandomAccessIterator __first,
    		  _RandomAccessIterator __middle,
    		  _RandomAccessIterator __last, _Compare __comp)
        {
          std::make_heap(__first, __middle, __comp);
          for (_RandomAccessIterator __i = __middle; __i < __last; ++__i)
    	if (__comp(*__i, *__first))
    	  std::__pop_heap(__first, __middle, __i, __comp);
        }
    
      // partial_sort
    
      /**
       *  @brief Copy the smallest elements of a sequence.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __result_first   A random-access iterator.
       *  @param  __result_last    Another random-access iterator.
       *  @return   An iterator indicating the end of the resulting sequence.
       *
       *  Copies and sorts the smallest N values from the range @p [__first,__last)
       *  to the range beginning at @p __result_first, where the number of
       *  elements to be copied, @p N, is the smaller of @p (__last-__first) and
       *  @p (__result_last-__result_first).
       *  After the sort if @e i and @e j are iterators in the range
       *  @p [__result_first,__result_first+N) such that i precedes j then
       *  *j<*i is false.
       *  The value returned is @p __result_first+N.
      */
      template<typename _InputIterator, typename _RandomAccessIterator>
        _RandomAccessIterator
        partial_sort_copy(_InputIterator __first, _InputIterator __last,
    		      _RandomAccessIterator __result_first,
    		      _RandomAccessIterator __result_last)
        {
          typedef typename iterator_traits<_InputIterator>::value_type
    	_InputValueType;
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_OutputValueType;
          typedef typename iterator_traits<_RandomAccessIterator>::difference_type
    	_DistanceType;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_ConvertibleConcept<_InputValueType,
    				  _OutputValueType>)
          __glibcxx_function_requires(_LessThanOpConcept<_InputValueType,
    				                     _OutputValueType>)
          __glibcxx_function_requires(_LessThanComparableConcept<_OutputValueType>)
          __glibcxx_requires_valid_range(__first, __last);
          __glibcxx_requires_valid_range(__result_first, __result_last);
    
          if (__result_first == __result_last)
    	return __result_last;
          _RandomAccessIterator __result_real_last = __result_first;
          while(__first != __last && __result_real_last != __result_last)
    	{
    	  *__result_real_last = *__first;
    	  ++__result_real_last;
    	  ++__first;
    	}
          std::make_heap(__result_first, __result_real_last);
          while (__first != __last)
    	{
    	  if (*__first < *__result_first)
    	    std::__adjust_heap(__result_first, _DistanceType(0),
    			       _DistanceType(__result_real_last
    					     - __result_first),
    			       _InputValueType(*__first));
    	  ++__first;
    	}
          std::sort_heap(__result_first, __result_real_last);
          return __result_real_last;
        }
    
      /**
       *  @brief Copy the smallest elements of a sequence using a predicate for
       *         comparison.
       *  @ingroup sorting_algorithms
       *  @param  __first   An input iterator.
       *  @param  __last    Another input iterator.
       *  @param  __result_first   A random-access iterator.
       *  @param  __result_last    Another random-access iterator.
       *  @param  __comp    A comparison functor.
       *  @return   An iterator indicating the end of the resulting sequence.
       *
       *  Copies and sorts the smallest N values from the range @p [__first,__last)
       *  to the range beginning at @p result_first, where the number of
       *  elements to be copied, @p N, is the smaller of @p (__last-__first) and
       *  @p (__result_last-__result_first).
       *  After the sort if @e i and @e j are iterators in the range
       *  @p [__result_first,__result_first+N) such that i precedes j then
       *  @p __comp(*j,*i) is false.
       *  The value returned is @p __result_first+N.
      */
      template<typename _InputIterator, typename _RandomAccessIterator, typename _Compare>
        _RandomAccessIterator
        partial_sort_copy(_InputIterator __first, _InputIterator __last,
    		      _RandomAccessIterator __result_first,
    		      _RandomAccessIterator __result_last,
    		      _Compare __comp)
        {
          typedef typename iterator_traits<_InputIterator>::value_type
    	_InputValueType;
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_OutputValueType;
          typedef typename iterator_traits<_RandomAccessIterator>::difference_type
    	_DistanceType;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    				  _RandomAccessIterator>)
          __glibcxx_function_requires(_ConvertibleConcept<_InputValueType,
    				  _OutputValueType>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _InputValueType, _OutputValueType>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _OutputValueType, _OutputValueType>)
          __glibcxx_requires_valid_range(__first, __last);
          __glibcxx_requires_valid_range(__result_first, __result_last);
    
          if (__result_first == __result_last)
    	return __result_last;
          _RandomAccessIterator __result_real_last = __result_first;
          while(__first != __last && __result_real_last != __result_last)
    	{
    	  *__result_real_last = *__first;
    	  ++__result_real_last;
    	  ++__first;
    	}
          std::make_heap(__result_first, __result_real_last, __comp);
          while (__first != __last)
    	{
    	  if (__comp(*__first, *__result_first))
    	    std::__adjust_heap(__result_first, _DistanceType(0),
    			       _DistanceType(__result_real_last
    					     - __result_first),
    			       _InputValueType(*__first),
    			       __comp);
    	  ++__first;
    	}
          std::sort_heap(__result_first, __result_real_last, __comp);
          return __result_real_last;
        }
    
      /// This is a helper function for the sort routine.
      template<typename _RandomAccessIterator>
        void
        __unguarded_linear_insert(_RandomAccessIterator __last)
        {
          typename iterator_traits<_RandomAccessIterator>::value_type
    	__val = _GLIBCXX_MOVE(*__last);
          _RandomAccessIterator __next = __last;
          --__next;
          while (__val < *__next)
    	{
    	  *__last = _GLIBCXX_MOVE(*__next);
    	  __last = __next;
    	  --__next;
    	}
          *__last = _GLIBCXX_MOVE(__val);
        }
    
      /// This is a helper function for the sort routine.
      template<typename _RandomAccessIterator, typename _Compare>
        void
        __unguarded_linear_insert(_RandomAccessIterator __last,
    			      _Compare __comp)
        {
          typename iterator_traits<_RandomAccessIterator>::value_type
    	__val = _GLIBCXX_MOVE(*__last);
          _RandomAccessIterator __next = __last;
          --__next;
          while (__comp(__val, *__next))
    	{
    	  *__last = _GLIBCXX_MOVE(*__next);
    	  __last = __next;
    	  --__next;
    	}
          *__last = _GLIBCXX_MOVE(__val);
        }
    
      /// This is a helper function for the sort routine.
      template<typename _RandomAccessIterator>
        void
        __insertion_sort(_RandomAccessIterator __first,
    		     _RandomAccessIterator __last)
        {
          if (__first == __last)
    	return;
    
          for (_RandomAccessIterator __i = __first + 1; __i != __last; ++__i)
    	{
    	  if (*__i < *__first)
    	    {
    	      typename iterator_traits<_RandomAccessIterator>::value_type
    		__val = _GLIBCXX_MOVE(*__i);
    	      _GLIBCXX_MOVE_BACKWARD3(__first, __i, __i + 1);
    	      *__first = _GLIBCXX_MOVE(__val);
    	    }
    	  else
    	    std::__unguarded_linear_insert(__i);
    	}
        }
    
      /// This is a helper function for the sort routine.
      template<typename _RandomAccessIterator, typename _Compare>
        void
        __insertion_sort(_RandomAccessIterator __first,
    		     _RandomAccessIterator __last, _Compare __comp)
        {
          if (__first == __last) return;
    
          for (_RandomAccessIterator __i = __first + 1; __i != __last; ++__i)
    	{
    	  if (__comp(*__i, *__first))
    	    {
    	      typename iterator_traits<_RandomAccessIterator>::value_type
    		__val = _GLIBCXX_MOVE(*__i);
    	      _GLIBCXX_MOVE_BACKWARD3(__first, __i, __i + 1);
    	      *__first = _GLIBCXX_MOVE(__val);
    	    }
    	  else
    	    std::__unguarded_linear_insert(__i, __comp);
    	}
        }
    
      /// This is a helper function for the sort routine.
      template<typename _RandomAccessIterator>
        inline void
        __unguarded_insertion_sort(_RandomAccessIterator __first,
    			       _RandomAccessIterator __last)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
    
          for (_RandomAccessIterator __i = __first; __i != __last; ++__i)
    	std::__unguarded_linear_insert(__i);
        }
    
      /// This is a helper function for the sort routine.
      template<typename _RandomAccessIterator, typename _Compare>
        inline void
        __unguarded_insertion_sort(_RandomAccessIterator __first,
    			       _RandomAccessIterator __last, _Compare __comp)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
    
          for (_RandomAccessIterator __i = __first; __i != __last; ++__i)
    	std::__unguarded_linear_insert(__i, __comp);
        }
    
      /**
       *  @doctodo
       *  This controls some aspect of the sort routines.
      */
      enum { _S_threshold = 16 };
    
      /// This is a helper function for the sort routine.
      template<typename _RandomAccessIterator>
        void
        __final_insertion_sort(_RandomAccessIterator __first,
    			   _RandomAccessIterator __last)
        {
          if (__last - __first > int(_S_threshold))
    	{
    	  std::__insertion_sort(__first, __first + int(_S_threshold));
    	  std::__unguarded_insertion_sort(__first + int(_S_threshold), __last);
    	}
          else
    	std::__insertion_sort(__first, __last);
        }
    
      /// This is a helper function for the sort routine.
      template<typename _RandomAccessIterator, typename _Compare>
        void
        __final_insertion_sort(_RandomAccessIterator __first,
    			   _RandomAccessIterator __last, _Compare __comp)
        {
          if (__last - __first > int(_S_threshold))
    	{
    	  std::__insertion_sort(__first, __first + int(_S_threshold), __comp);
    	  std::__unguarded_insertion_sort(__first + int(_S_threshold), __last,
    					  __comp);
    	}
          else
    	std::__insertion_sort(__first, __last, __comp);
        }
    
      /// This is a helper function...
      template<typename _RandomAccessIterator, typename _Tp>
        _RandomAccessIterator
        __unguarded_partition(_RandomAccessIterator __first,
    			  _RandomAccessIterator __last, const _Tp& __pivot)
        {
          while (true)
    	{
    	  while (*__first < __pivot)
    	    ++__first;
    	  --__last;
    	  while (__pivot < *__last)
    	    --__last;
    	  if (!(__first < __last))
    	    return __first;
    	  std::iter_swap(__first, __last);
    	  ++__first;
    	}
        }
    
      /// This is a helper function...
      template<typename _RandomAccessIterator, typename _Tp, typename _Compare>
        _RandomAccessIterator
        __unguarded_partition(_RandomAccessIterator __first,
    			  _RandomAccessIterator __last,
    			  const _Tp& __pivot, _Compare __comp)
        {
          while (true)
    	{
    	  while (__comp(*__first, __pivot))
    	    ++__first;
    	  --__last;
    	  while (__comp(__pivot, *__last))
    	    --__last;
    	  if (!(__first < __last))
    	    return __first;
    	  std::iter_swap(__first, __last);
    	  ++__first;
    	}
        }
    
      /// This is a helper function...
      template<typename _RandomAccessIterator>
        inline _RandomAccessIterator
        __unguarded_partition_pivot(_RandomAccessIterator __first,
    				_RandomAccessIterator __last)
        {
          _RandomAccessIterator __mid = __first + (__last - __first) / 2;
          std::__move_median_first(__first, __mid, (__last - 1));
          return std::__unguarded_partition(__first + 1, __last, *__first);
        }
    
    
      /// This is a helper function...
      template<typename _RandomAccessIterator, typename _Compare>
        inline _RandomAccessIterator
        __unguarded_partition_pivot(_RandomAccessIterator __first,
    				_RandomAccessIterator __last, _Compare __comp)
        {
          _RandomAccessIterator __mid = __first + (__last - __first) / 2;
          std::__move_median_first(__first, __mid, (__last - 1), __comp);
          return std::__unguarded_partition(__first + 1, __last, *__first, __comp);
        }
    
      /// This is a helper function for the sort routine.
      template<typename _RandomAccessIterator, typename _Size>
        void
        __introsort_loop(_RandomAccessIterator __first,
    		     _RandomAccessIterator __last,
    		     _Size __depth_limit)
        {
          while (__last - __first > int(_S_threshold))
    	{
    	  if (__depth_limit == 0)
    	    {
    	      _GLIBCXX_STD_A::partial_sort(__first, __last, __last);
    	      return;
    	    }
    	  --__depth_limit;
    	  _RandomAccessIterator __cut =
    	    std::__unguarded_partition_pivot(__first, __last);
    	  std::__introsort_loop(__cut, __last, __depth_limit);
    	  __last = __cut;
    	}
        }
    
      /// This is a helper function for the sort routine.
      template<typename _RandomAccessIterator, typename _Size, typename _Compare>
        void
        __introsort_loop(_RandomAccessIterator __first,
    		     _RandomAccessIterator __last,
    		     _Size __depth_limit, _Compare __comp)
        {
          while (__last - __first > int(_S_threshold))
    	{
    	  if (__depth_limit == 0)
    	    {
    	      _GLIBCXX_STD_A::partial_sort(__first, __last, __last, __comp);
    	      return;
    	    }
    	  --__depth_limit;
    	  _RandomAccessIterator __cut =
    	    std::__unguarded_partition_pivot(__first, __last, __comp);
    	  std::__introsort_loop(__cut, __last, __depth_limit, __comp);
    	  __last = __cut;
    	}
        }
    
      // sort
    
      template<typename _RandomAccessIterator, typename _Size>
        void
        __introselect(_RandomAccessIterator __first, _RandomAccessIterator __nth,
    		  _RandomAccessIterator __last, _Size __depth_limit)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
    
          while (__last - __first > 3)
    	{
    	  if (__depth_limit == 0)
    	    {
    	      std::__heap_select(__first, __nth + 1, __last);
    
    	      // Place the nth largest element in its final position.
    	      std::iter_swap(__first, __nth);
    	      return;
    	    }
    	  --__depth_limit;
    	  _RandomAccessIterator __cut =
    	    std::__unguarded_partition_pivot(__first, __last);
    	  if (__cut <= __nth)
    	    __first = __cut;
    	  else
    	    __last = __cut;
    	}
          std::__insertion_sort(__first, __last);
        }
    
      template<typename _RandomAccessIterator, typename _Size, typename _Compare>
        void
        __introselect(_RandomAccessIterator __first, _RandomAccessIterator __nth,
    		  _RandomAccessIterator __last, _Size __depth_limit,
    		  _Compare __comp)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
    
          while (__last - __first > 3)
    	{
    	  if (__depth_limit == 0)
    	    {
    	      std::__heap_select(__first, __nth + 1, __last, __comp);
    	      // Place the nth largest element in its final position.
    	      std::iter_swap(__first, __nth);
    	      return;
    	    }
    	  --__depth_limit;
    	  _RandomAccessIterator __cut =
    	    std::__unguarded_partition_pivot(__first, __last, __comp);
    	  if (__cut <= __nth)
    	    __first = __cut;
    	  else
    	    __last = __cut;
    	}
          std::__insertion_sort(__first, __last, __comp);
        }
    
      // nth_element
    
      // lower_bound moved to stl_algobase.h
    
      /**
       *  @brief Finds the first position in which @p __val could be inserted
       *         without changing the ordering.
       *  @ingroup binary_search_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __val     The search term.
       *  @param  __comp    A functor to use for comparisons.
       *  @return An iterator pointing to the first element <em>not less
       *           than</em> @p __val, or end() if every element is less
       *           than @p __val.
       *  @ingroup binary_search_algorithms
       *
       *  The comparison function should have the same effects on ordering as
       *  the function used for the initial sort.
      */
      template<typename _ForwardIterator, typename _Tp, typename _Compare>
        _ForwardIterator
        lower_bound(_ForwardIterator __first, _ForwardIterator __last,
    		const _Tp& __val, _Compare __comp)
        {
          typedef typename iterator_traits<_ForwardIterator>::value_type
    	_ValueType;
          typedef typename iterator_traits<_ForwardIterator>::difference_type
    	_DistanceType;
    
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType, _Tp>)
          __glibcxx_requires_partitioned_lower_pred(__first, __last,
    						__val, __comp);
    
          _DistanceType __len = std::distance(__first, __last);
    
          while (__len > 0)
    	{
    	  _DistanceType __half = __len >> 1;
    	  _ForwardIterator __middle = __first;
    	  std::advance(__middle, __half);
    	  if (__comp(*__middle, __val))
    	    {
    	      __first = __middle;
    	      ++__first;
    	      __len = __len - __half - 1;
    	    }
    	  else
    	    __len = __half;
    	}
          return __first;
        }
    
      /**
       *  @brief Finds the last position in which @p __val could be inserted
       *         without changing the ordering.
       *  @ingroup binary_search_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __val     The search term.
       *  @return  An iterator pointing to the first element greater than @p __val,
       *           or end() if no elements are greater than @p __val.
       *  @ingroup binary_search_algorithms
      */
      template<typename _ForwardIterator, typename _Tp>
        _ForwardIterator
        upper_bound(_ForwardIterator __first, _ForwardIterator __last,
    		const _Tp& __val)
        {
          typedef typename iterator_traits<_ForwardIterator>::value_type
    	_ValueType;
          typedef typename iterator_traits<_ForwardIterator>::difference_type
    	_DistanceType;
    
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_LessThanOpConcept<_Tp, _ValueType>)
          __glibcxx_requires_partitioned_upper(__first, __last, __val);
    
          _DistanceType __len = std::distance(__first, __last);
    
          while (__len > 0)
    	{
    	  _DistanceType __half = __len >> 1;
    	  _ForwardIterator __middle = __first;
    	  std::advance(__middle, __half);
    	  if (__val < *__middle)
    	    __len = __half;
    	  else
    	    {
    	      __first = __middle;
    	      ++__first;
    	      __len = __len - __half - 1;
    	    }
    	}
          return __first;
        }
    
      /**
       *  @brief Finds the last position in which @p __val could be inserted
       *         without changing the ordering.
       *  @ingroup binary_search_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __val     The search term.
       *  @param  __comp    A functor to use for comparisons.
       *  @return  An iterator pointing to the first element greater than @p __val,
       *           or end() if no elements are greater than @p __val.
       *  @ingroup binary_search_algorithms
       *
       *  The comparison function should have the same effects on ordering as
       *  the function used for the initial sort.
      */
      template<typename _ForwardIterator, typename _Tp, typename _Compare>
        _ForwardIterator
        upper_bound(_ForwardIterator __first, _ForwardIterator __last,
    		const _Tp& __val, _Compare __comp)
        {
          typedef typename iterator_traits<_ForwardIterator>::value_type
    	_ValueType;
          typedef typename iterator_traits<_ForwardIterator>::difference_type
    	_DistanceType;
    
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _Tp, _ValueType>)
          __glibcxx_requires_partitioned_upper_pred(__first, __last,
    						__val, __comp);
    
          _DistanceType __len = std::distance(__first, __last);
    
          while (__len > 0)
    	{
    	  _DistanceType __half = __len >> 1;
    	  _ForwardIterator __middle = __first;
    	  std::advance(__middle, __half);
    	  if (__comp(__val, *__middle))
    	    __len = __half;
    	  else
    	    {
    	      __first = __middle;
    	      ++__first;
    	      __len = __len - __half - 1;
    	    }
    	}
          return __first;
        }
    
      /**
       *  @brief Finds the largest subrange in which @p __val could be inserted
       *         at any place in it without changing the ordering.
       *  @ingroup binary_search_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __val     The search term.
       *  @return  An pair of iterators defining the subrange.
       *  @ingroup binary_search_algorithms
       *
       *  This is equivalent to
       *  @code
       *    std::make_pair(lower_bound(__first, __last, __val),
       *                   upper_bound(__first, __last, __val))
       *  @endcode
       *  but does not actually call those functions.
      */
      template<typename _ForwardIterator, typename _Tp>
        pair<_ForwardIterator, _ForwardIterator>
        equal_range(_ForwardIterator __first, _ForwardIterator __last,
    		const _Tp& __val)
        {
          typedef typename iterator_traits<_ForwardIterator>::value_type
    	_ValueType;
          typedef typename iterator_traits<_ForwardIterator>::difference_type
    	_DistanceType;
    
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_LessThanOpConcept<_ValueType, _Tp>)
          __glibcxx_function_requires(_LessThanOpConcept<_Tp, _ValueType>)	
          __glibcxx_requires_partitioned_lower(__first, __last, __val);
          __glibcxx_requires_partitioned_upper(__first, __last, __val);      
    
          _DistanceType __len = std::distance(__first, __last);
     
          while (__len > 0)
    	{
    	  _DistanceType __half = __len >> 1;
    	  _ForwardIterator __middle = __first;
    	  std::advance(__middle, __half);
    	  if (*__middle < __val)
    	    {
    	      __first = __middle;
    	      ++__first;
    	      __len = __len - __half - 1;
    	    }
    	  else if (__val < *__middle)
    	    __len = __half;
    	  else
    	    {
    	      _ForwardIterator __left = std::lower_bound(__first, __middle,
    							 __val);
    	      std::advance(__first, __len);
    	      _ForwardIterator __right = std::upper_bound(++__middle, __first,
    							  __val);
    	      return pair<_ForwardIterator, _ForwardIterator>(__left, __right);
    	    }
    	}
          return pair<_ForwardIterator, _ForwardIterator>(__first, __first);
        }
    
      /**
       *  @brief Finds the largest subrange in which @p __val could be inserted
       *         at any place in it without changing the ordering.
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __val     The search term.
       *  @param  __comp    A functor to use for comparisons.
       *  @return  An pair of iterators defining the subrange.
       *  @ingroup binary_search_algorithms
       *
       *  This is equivalent to
       *  @code
       *    std::make_pair(lower_bound(__first, __last, __val, __comp),
       *                   upper_bound(__first, __last, __val, __comp))
       *  @endcode
       *  but does not actually call those functions.
      */
      template<typename _ForwardIterator, typename _Tp, typename _Compare>
        pair<_ForwardIterator, _ForwardIterator>
        equal_range(_ForwardIterator __first, _ForwardIterator __last,
    		const _Tp& __val, _Compare __comp)
        {
          typedef typename iterator_traits<_ForwardIterator>::value_type
    	_ValueType;
          typedef typename iterator_traits<_ForwardIterator>::difference_type
    	_DistanceType;
    
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType, _Tp>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _Tp, _ValueType>)
          __glibcxx_requires_partitioned_lower_pred(__first, __last,
    						__val, __comp);
          __glibcxx_requires_partitioned_upper_pred(__first, __last,
    						__val, __comp);
    
          _DistanceType __len = std::distance(__first, __last);
    
          while (__len > 0)
    	{
    	  _DistanceType __half = __len >> 1;
    	  _ForwardIterator __middle = __first;
    	  std::advance(__middle, __half);
    	  if (__comp(*__middle, __val))
    	    {
    	      __first = __middle;
    	      ++__first;
    	      __len = __len - __half - 1;
    	    }
    	  else if (__comp(__val, *__middle))
    	    __len = __half;
    	  else
    	    {
    	      _ForwardIterator __left = std::lower_bound(__first, __middle,
    							 __val, __comp);
    	      std::advance(__first, __len);
    	      _ForwardIterator __right = std::upper_bound(++__middle, __first,
    							  __val, __comp);
    	      return pair<_ForwardIterator, _ForwardIterator>(__left, __right);
    	    }
    	}
          return pair<_ForwardIterator, _ForwardIterator>(__first, __first);
        }
    
      /**
       *  @brief Determines whether an element exists in a range.
       *  @ingroup binary_search_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __val     The search term.
       *  @return True if @p __val (or its equivalent) is in [@p
       *  __first,@p __last ].
       *
       *  Note that this does not actually return an iterator to @p __val.  For
       *  that, use std::find or a container's specialized find member functions.
      */
      template<typename _ForwardIterator, typename _Tp>
        bool
        binary_search(_ForwardIterator __first, _ForwardIterator __last,
                      const _Tp& __val)
        {
          typedef typename iterator_traits<_ForwardIterator>::value_type
    	_ValueType;
    
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_LessThanOpConcept<_Tp, _ValueType>)
          __glibcxx_requires_partitioned_lower(__first, __last, __val);
          __glibcxx_requires_partitioned_upper(__first, __last, __val);
    
          _ForwardIterator __i = std::lower_bound(__first, __last, __val);
          return __i != __last && !(__val < *__i);
        }
    
      /**
       *  @brief Determines whether an element exists in a range.
       *  @ingroup binary_search_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __val     The search term.
       *  @param  __comp    A functor to use for comparisons.
       *  @return  True if @p __val (or its equivalent) is in @p [__first,__last].
       *
       *  Note that this does not actually return an iterator to @p __val.  For
       *  that, use std::find or a container's specialized find member functions.
       *
       *  The comparison function should have the same effects on ordering as
       *  the function used for the initial sort.
      */
      template<typename _ForwardIterator, typename _Tp, typename _Compare>
        bool
        binary_search(_ForwardIterator __first, _ForwardIterator __last,
                      const _Tp& __val, _Compare __comp)
        {
          typedef typename iterator_traits<_ForwardIterator>::value_type
    	_ValueType;
    
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _Tp, _ValueType>)
          __glibcxx_requires_partitioned_lower_pred(__first, __last,
    						__val, __comp);
          __glibcxx_requires_partitioned_upper_pred(__first, __last,
    						__val, __comp);
    
          _ForwardIterator __i = std::lower_bound(__first, __last, __val, __comp);
          return __i != __last && !bool(__comp(__val, *__i));
        }
    
      // merge
    
      /// This is a helper function for the __merge_adaptive routines.
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator>
        void
        __move_merge_adaptive(_InputIterator1 __first1, _InputIterator1 __last1,
    			  _InputIterator2 __first2, _InputIterator2 __last2,
    			  _OutputIterator __result)
        {
          while (__first1 != __last1 && __first2 != __last2)
    	{
    	  if (*__first2 < *__first1)
    	    {
    	      *__result = _GLIBCXX_MOVE(*__first2);
    	      ++__first2;
    	    }
    	  else
    	    {
    	      *__result = _GLIBCXX_MOVE(*__first1);
    	      ++__first1;
    	    }
    	  ++__result;
    	}
          if (__first1 != __last1)
    	_GLIBCXX_MOVE3(__first1, __last1, __result);
        }
    
      /// This is a helper function for the __merge_adaptive routines.
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator, typename _Compare>
        void
        __move_merge_adaptive(_InputIterator1 __first1, _InputIterator1 __last1,
    			  _InputIterator2 __first2, _InputIterator2 __last2,
    			  _OutputIterator __result, _Compare __comp)
        {
          while (__first1 != __last1 && __first2 != __last2)
    	{
    	  if (__comp(*__first2, *__first1))
    	    {
    	      *__result = _GLIBCXX_MOVE(*__first2);
    	      ++__first2;
    	    }
    	  else
    	    {
    	      *__result = _GLIBCXX_MOVE(*__first1);
    	      ++__first1;
    	    }
    	  ++__result;
    	}
          if (__first1 != __last1)
    	_GLIBCXX_MOVE3(__first1, __last1, __result);
        }
    
      /// This is a helper function for the __merge_adaptive routines.
      template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,
    	   typename _BidirectionalIterator3>
        void
        __move_merge_adaptive_backward(_BidirectionalIterator1 __first1,
    				   _BidirectionalIterator1 __last1,
    				   _BidirectionalIterator2 __first2,
    				   _BidirectionalIterator2 __last2,
    				   _BidirectionalIterator3 __result)
        {
          if (__first1 == __last1)
    	{
    	  _GLIBCXX_MOVE_BACKWARD3(__first2, __last2, __result);
    	  return;
    	}
          else if (__first2 == __last2)
    	return;
    
          --__last1;
          --__last2;
          while (true)
    	{
    	  if (*__last2 < *__last1)
    	    {
    	      *--__result = _GLIBCXX_MOVE(*__last1);
    	      if (__first1 == __last1)
    		{
    		  _GLIBCXX_MOVE_BACKWARD3(__first2, ++__last2, __result);
    		  return;
    		}
    	      --__last1;
    	    }
    	  else
    	    {
    	      *--__result = _GLIBCXX_MOVE(*__last2);
    	      if (__first2 == __last2)
    		return;
    	      --__last2;
    	    }
    	}
        }
    
      /// This is a helper function for the __merge_adaptive routines.
      template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,
    	   typename _BidirectionalIterator3, typename _Compare>
        void
        __move_merge_adaptive_backward(_BidirectionalIterator1 __first1,
    				   _BidirectionalIterator1 __last1,
    				   _BidirectionalIterator2 __first2,
    				   _BidirectionalIterator2 __last2,
    				   _BidirectionalIterator3 __result,
    				   _Compare __comp)
        {
          if (__first1 == __last1)
    	{
    	  _GLIBCXX_MOVE_BACKWARD3(__first2, __last2, __result);
    	  return;
    	}
          else if (__first2 == __last2)
    	return;
    
          --__last1;
          --__last2;
          while (true)
    	{
    	  if (__comp(*__last2, *__last1))
    	    {
    	      *--__result = _GLIBCXX_MOVE(*__last1);
    	      if (__first1 == __last1)
    		{
    		  _GLIBCXX_MOVE_BACKWARD3(__first2, ++__last2, __result);
    		  return;
    		}
    	      --__last1;
    	    }
    	  else
    	    {
    	      *--__result = _GLIBCXX_MOVE(*__last2);
    	      if (__first2 == __last2)
    		return;
    	      --__last2;
    	    }
    	}
        }
    
      /// This is a helper function for the merge routines.
      template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,
    	   typename _Distance>
        _BidirectionalIterator1
        __rotate_adaptive(_BidirectionalIterator1 __first,
    		      _BidirectionalIterator1 __middle,
    		      _BidirectionalIterator1 __last,
    		      _Distance __len1, _Distance __len2,
    		      _BidirectionalIterator2 __buffer,
    		      _Distance __buffer_size)
        {
          _BidirectionalIterator2 __buffer_end;
          if (__len1 > __len2 && __len2 <= __buffer_size)
    	{
    	  if (__len2)
    	    {
    	      __buffer_end = _GLIBCXX_MOVE3(__middle, __last, __buffer);
    	      _GLIBCXX_MOVE_BACKWARD3(__first, __middle, __last);
    	      return _GLIBCXX_MOVE3(__buffer, __buffer_end, __first);
    	    }
    	  else
    	    return __first;
    	}
          else if (__len1 <= __buffer_size)
    	{
    	  if (__len1)
    	    {
    	      __buffer_end = _GLIBCXX_MOVE3(__first, __middle, __buffer);
    	      _GLIBCXX_MOVE3(__middle, __last, __first);
    	      return _GLIBCXX_MOVE_BACKWARD3(__buffer, __buffer_end, __last);
    	    }
    	  else
    	    return __last;
    	}
          else
    	{
    	  std::rotate(__first, __middle, __last);
    	  std::advance(__first, std::distance(__middle, __last));
    	  return __first;
    	}
        }
    
      /// This is a helper function for the merge routines.
      template<typename _BidirectionalIterator, typename _Distance,
    	   typename _Pointer>
        void
        __merge_adaptive(_BidirectionalIterator __first,
                         _BidirectionalIterator __middle,
    		     _BidirectionalIterator __last,
    		     _Distance __len1, _Distance __len2,
    		     _Pointer __buffer, _Distance __buffer_size)
        {
          if (__len1 <= __len2 && __len1 <= __buffer_size)
    	{
    	  _Pointer __buffer_end = _GLIBCXX_MOVE3(__first, __middle, __buffer);
    	  std::__move_merge_adaptive(__buffer, __buffer_end, __middle, __last,
    				     __first);
    	}
          else if (__len2 <= __buffer_size)
    	{
    	  _Pointer __buffer_end = _GLIBCXX_MOVE3(__middle, __last, __buffer);
    	  std::__move_merge_adaptive_backward(__first, __middle, __buffer,
    					      __buffer_end, __last);
    	}
          else
    	{
    	  _BidirectionalIterator __first_cut = __first;
    	  _BidirectionalIterator __second_cut = __middle;
    	  _Distance __len11 = 0;
    	  _Distance __len22 = 0;
    	  if (__len1 > __len2)
    	    {
    	      __len11 = __len1 / 2;
    	      std::advance(__first_cut, __len11);
    	      __second_cut = std::lower_bound(__middle, __last,
    					      *__first_cut);
    	      __len22 = std::distance(__middle, __second_cut);
    	    }
    	  else
    	    {
    	      __len22 = __len2 / 2;
    	      std::advance(__second_cut, __len22);
    	      __first_cut = std::upper_bound(__first, __middle,
    					     *__second_cut);
    	      __len11 = std::distance(__first, __first_cut);
    	    }
    	  _BidirectionalIterator __new_middle =
    	    std::__rotate_adaptive(__first_cut, __middle, __second_cut,
    				   __len1 - __len11, __len22, __buffer,
    				   __buffer_size);
    	  std::__merge_adaptive(__first, __first_cut, __new_middle, __len11,
    				__len22, __buffer, __buffer_size);
    	  std::__merge_adaptive(__new_middle, __second_cut, __last,
    				__len1 - __len11,
    				__len2 - __len22, __buffer, __buffer_size);
    	}
        }
    
      /// This is a helper function for the merge routines.
      template<typename _BidirectionalIterator, typename _Distance, 
    	   typename _Pointer, typename _Compare>
        void
        __merge_adaptive(_BidirectionalIterator __first,
                         _BidirectionalIterator __middle,
    		     _BidirectionalIterator __last,
    		     _Distance __len1, _Distance __len2,
    		     _Pointer __buffer, _Distance __buffer_size,
    		     _Compare __comp)
        {
          if (__len1 <= __len2 && __len1 <= __buffer_size)
    	{
    	  _Pointer __buffer_end = _GLIBCXX_MOVE3(__first, __middle, __buffer);
    	  std::__move_merge_adaptive(__buffer, __buffer_end, __middle, __last,
    				     __first, __comp);
    	}
          else if (__len2 <= __buffer_size)
    	{
    	  _Pointer __buffer_end = _GLIBCXX_MOVE3(__middle, __last, __buffer);
    	  std::__move_merge_adaptive_backward(__first, __middle, __buffer,
    					      __buffer_end, __last, __comp);
    	}
          else
    	{
    	  _BidirectionalIterator __first_cut = __first;
    	  _BidirectionalIterator __second_cut = __middle;
    	  _Distance __len11 = 0;
    	  _Distance __len22 = 0;
    	  if (__len1 > __len2)
    	    {
    	      __len11 = __len1 / 2;
    	      std::advance(__first_cut, __len11);
    	      __second_cut = std::lower_bound(__middle, __last, *__first_cut,
    					      __comp);
    	      __len22 = std::distance(__middle, __second_cut);
    	    }
    	  else
    	    {
    	      __len22 = __len2 / 2;
    	      std::advance(__second_cut, __len22);
    	      __first_cut = std::upper_bound(__first, __middle, *__second_cut,
    					     __comp);
    	      __len11 = std::distance(__first, __first_cut);
    	    }
    	  _BidirectionalIterator __new_middle =
    	    std::__rotate_adaptive(__first_cut, __middle, __second_cut,
    				   __len1 - __len11, __len22, __buffer,
    				   __buffer_size);
    	  std::__merge_adaptive(__first, __first_cut, __new_middle, __len11,
    				__len22, __buffer, __buffer_size, __comp);
    	  std::__merge_adaptive(__new_middle, __second_cut, __last,
    				__len1 - __len11,
    				__len2 - __len22, __buffer,
    				__buffer_size, __comp);
    	}
        }
    
      /// This is a helper function for the merge routines.
      template<typename _BidirectionalIterator, typename _Distance>
        void
        __merge_without_buffer(_BidirectionalIterator __first,
    			   _BidirectionalIterator __middle,
    			   _BidirectionalIterator __last,
    			   _Distance __len1, _Distance __len2)
        {
          if (__len1 == 0 || __len2 == 0)
    	return;
          if (__len1 + __len2 == 2)
    	{
    	  if (*__middle < *__first)
    	    std::iter_swap(__first, __middle);
    	  return;
    	}
          _BidirectionalIterator __first_cut = __first;
          _BidirectionalIterator __second_cut = __middle;
          _Distance __len11 = 0;
          _Distance __len22 = 0;
          if (__len1 > __len2)
    	{
    	  __len11 = __len1 / 2;
    	  std::advance(__first_cut, __len11);
    	  __second_cut = std::lower_bound(__middle, __last, *__first_cut);
    	  __len22 = std::distance(__middle, __second_cut);
    	}
          else
    	{
    	  __len22 = __len2 / 2;
    	  std::advance(__second_cut, __len22);
    	  __first_cut = std::upper_bound(__first, __middle, *__second_cut);
    	  __len11 = std::distance(__first, __first_cut);
    	}
          std::rotate(__first_cut, __middle, __second_cut);
          _BidirectionalIterator __new_middle = __first_cut;
          std::advance(__new_middle, std::distance(__middle, __second_cut));
          std::__merge_without_buffer(__first, __first_cut, __new_middle,
    				  __len11, __len22);
          std::__merge_without_buffer(__new_middle, __second_cut, __last,
    				  __len1 - __len11, __len2 - __len22);
        }
    
      /// This is a helper function for the merge routines.
      template<typename _BidirectionalIterator, typename _Distance,
    	   typename _Compare>
        void
        __merge_without_buffer(_BidirectionalIterator __first,
                               _BidirectionalIterator __middle,
    			   _BidirectionalIterator __last,
    			   _Distance __len1, _Distance __len2,
    			   _Compare __comp)
        {
          if (__len1 == 0 || __len2 == 0)
    	return;
          if (__len1 + __len2 == 2)
    	{
    	  if (__comp(*__middle, *__first))
    	    std::iter_swap(__first, __middle);
    	  return;
    	}
          _BidirectionalIterator __first_cut = __first;
          _BidirectionalIterator __second_cut = __middle;
          _Distance __len11 = 0;
          _Distance __len22 = 0;
          if (__len1 > __len2)
    	{
    	  __len11 = __len1 / 2;
    	  std::advance(__first_cut, __len11);
    	  __second_cut = std::lower_bound(__middle, __last, *__first_cut,
    					  __comp);
    	  __len22 = std::distance(__middle, __second_cut);
    	}
          else
    	{
    	  __len22 = __len2 / 2;
    	  std::advance(__second_cut, __len22);
    	  __first_cut = std::upper_bound(__first, __middle, *__second_cut,
    					 __comp);
    	  __len11 = std::distance(__first, __first_cut);
    	}
          std::rotate(__first_cut, __middle, __second_cut);
          _BidirectionalIterator __new_middle = __first_cut;
          std::advance(__new_middle, std::distance(__middle, __second_cut));
          std::__merge_without_buffer(__first, __first_cut, __new_middle,
    				  __len11, __len22, __comp);
          std::__merge_without_buffer(__new_middle, __second_cut, __last,
    				  __len1 - __len11, __len2 - __len22, __comp);
        }
    
      /**
       *  @brief Merges two sorted ranges in place.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __middle  Another iterator.
       *  @param  __last    Another iterator.
       *  @return  Nothing.
       *
       *  Merges two sorted and consecutive ranges, [__first,__middle) and
       *  [__middle,__last), and puts the result in [__first,__last).  The
       *  output will be sorted.  The sort is @e stable, that is, for
       *  equivalent elements in the two ranges, elements from the first
       *  range will always come before elements from the second.
       *
       *  If enough additional memory is available, this takes (__last-__first)-1
       *  comparisons.  Otherwise an NlogN algorithm is used, where N is
       *  distance(__first,__last).
      */
      template<typename _BidirectionalIterator>
        void
        inplace_merge(_BidirectionalIterator __first,
    		  _BidirectionalIterator __middle,
    		  _BidirectionalIterator __last)
        {
          typedef typename iterator_traits<_BidirectionalIterator>::value_type
              _ValueType;
          typedef typename iterator_traits<_BidirectionalIterator>::difference_type
              _DistanceType;
    
          // concept requirements
          __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
    	    _BidirectionalIterator>)
          __glibcxx_function_requires(_LessThanComparableConcept<_ValueType>)
          __glibcxx_requires_sorted(__first, __middle);
          __glibcxx_requires_sorted(__middle, __last);
    
          if (__first == __middle || __middle == __last)
    	return;
    
          _DistanceType __len1 = std::distance(__first, __middle);
          _DistanceType __len2 = std::distance(__middle, __last);
    
          _Temporary_buffer<_BidirectionalIterator, _ValueType> __buf(__first,
    								  __last);
          if (__buf.begin() == 0)
    	std::__merge_without_buffer(__first, __middle, __last, __len1, __len2);
          else
    	std::__merge_adaptive(__first, __middle, __last, __len1, __len2,
    			      __buf.begin(), _DistanceType(__buf.size()));
        }
    
      /**
       *  @brief Merges two sorted ranges in place.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __middle  Another iterator.
       *  @param  __last    Another iterator.
       *  @param  __comp    A functor to use for comparisons.
       *  @return  Nothing.
       *
       *  Merges two sorted and consecutive ranges, [__first,__middle) and
       *  [middle,last), and puts the result in [__first,__last).  The output will
       *  be sorted.  The sort is @e stable, that is, for equivalent
       *  elements in the two ranges, elements from the first range will always
       *  come before elements from the second.
       *
       *  If enough additional memory is available, this takes (__last-__first)-1
       *  comparisons.  Otherwise an NlogN algorithm is used, where N is
       *  distance(__first,__last).
       *
       *  The comparison function should have the same effects on ordering as
       *  the function used for the initial sort.
      */
      template<typename _BidirectionalIterator, typename _Compare>
        void
        inplace_merge(_BidirectionalIterator __first,
    		  _BidirectionalIterator __middle,
    		  _BidirectionalIterator __last,
    		  _Compare __comp)
        {
          typedef typename iterator_traits<_BidirectionalIterator>::value_type
              _ValueType;
          typedef typename iterator_traits<_BidirectionalIterator>::difference_type
              _DistanceType;
    
          // concept requirements
          __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<
    	    _BidirectionalIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    	    _ValueType, _ValueType>)
          __glibcxx_requires_sorted_pred(__first, __middle, __comp);
          __glibcxx_requires_sorted_pred(__middle, __last, __comp);
    
          if (__first == __middle || __middle == __last)
    	return;
    
          const _DistanceType __len1 = std::distance(__first, __middle);
          const _DistanceType __len2 = std::distance(__middle, __last);
    
          _Temporary_buffer<_BidirectionalIterator, _ValueType> __buf(__first,
    								  __last);
          if (__buf.begin() == 0)
    	std::__merge_without_buffer(__first, __middle, __last, __len1,
    				    __len2, __comp);
          else
    	std::__merge_adaptive(__first, __middle, __last, __len1, __len2,
    			      __buf.begin(), _DistanceType(__buf.size()),
    			      __comp);
        }
    
    
      /// This is a helper function for the __merge_sort_loop routines.
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator>
        _OutputIterator
        __move_merge(_InputIterator1 __first1, _InputIterator1 __last1,
    		 _InputIterator2 __first2, _InputIterator2 __last2,
    		 _OutputIterator __result)
        {
          while (__first1 != __last1 && __first2 != __last2)
    	{
    	  if (*__first2 < *__first1)
    	    {
    	      *__result = _GLIBCXX_MOVE(*__first2);
    	      ++__first2;
    	    }
    	  else
    	    {
    	      *__result = _GLIBCXX_MOVE(*__first1);
    	      ++__first1;
    	    }
    	  ++__result;
    	}
          return _GLIBCXX_MOVE3(__first2, __last2,
    			    _GLIBCXX_MOVE3(__first1, __last1,
    					   __result));
        }
    
      /// This is a helper function for the __merge_sort_loop routines.
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator, typename _Compare>
        _OutputIterator
        __move_merge(_InputIterator1 __first1, _InputIterator1 __last1,
    		 _InputIterator2 __first2, _InputIterator2 __last2,
    		 _OutputIterator __result, _Compare __comp)
        {
          while (__first1 != __last1 && __first2 != __last2)
    	{
    	  if (__comp(*__first2, *__first1))
    	    {
    	      *__result = _GLIBCXX_MOVE(*__first2);
    	      ++__first2;
    	    }
    	  else
    	    {
    	      *__result = _GLIBCXX_MOVE(*__first1);
    	      ++__first1;
    	    }
    	  ++__result;
    	}
          return _GLIBCXX_MOVE3(__first2, __last2,
    			    _GLIBCXX_MOVE3(__first1, __last1,
    					   __result));
        }
    
      template<typename _RandomAccessIterator1, typename _RandomAccessIterator2,
    	   typename _Distance>
        void
        __merge_sort_loop(_RandomAccessIterator1 __first,
    		      _RandomAccessIterator1 __last,
    		      _RandomAccessIterator2 __result,
    		      _Distance __step_size)
        {
          const _Distance __two_step = 2 * __step_size;
    
          while (__last - __first >= __two_step)
    	{
    	  __result = std::__move_merge(__first, __first + __step_size,
    				       __first + __step_size,
    				       __first + __two_step, __result);
    	  __first += __two_step;
    	}
    
          __step_size = std::min(_Distance(__last - __first), __step_size);
          std::__move_merge(__first, __first + __step_size,
    			__first + __step_size, __last, __result);
        }
    
      template<typename _RandomAccessIterator1, typename _RandomAccessIterator2,
    	   typename _Distance, typename _Compare>
        void
        __merge_sort_loop(_RandomAccessIterator1 __first,
    		      _RandomAccessIterator1 __last,
    		      _RandomAccessIterator2 __result, _Distance __step_size,
    		      _Compare __comp)
        {
          const _Distance __two_step = 2 * __step_size;
    
          while (__last - __first >= __two_step)
    	{
    	  __result = std::__move_merge(__first, __first + __step_size,
    				       __first + __step_size,
    				       __first + __two_step,
    				       __result, __comp);
    	  __first += __two_step;
    	}
          __step_size = std::min(_Distance(__last - __first), __step_size);
    
          std::__move_merge(__first,__first + __step_size,
    			__first + __step_size, __last, __result, __comp);
        }
    
      template<typename _RandomAccessIterator, typename _Distance>
        void
        __chunk_insertion_sort(_RandomAccessIterator __first,
    			   _RandomAccessIterator __last,
    			   _Distance __chunk_size)
        {
          while (__last - __first >= __chunk_size)
    	{
    	  std::__insertion_sort(__first, __first + __chunk_size);
    	  __first += __chunk_size;
    	}
          std::__insertion_sort(__first, __last);
        }
    
      template<typename _RandomAccessIterator, typename _Distance,
    	   typename _Compare>
        void
        __chunk_insertion_sort(_RandomAccessIterator __first,
    			   _RandomAccessIterator __last,
    			   _Distance __chunk_size, _Compare __comp)
        {
          while (__last - __first >= __chunk_size)
    	{
    	  std::__insertion_sort(__first, __first + __chunk_size, __comp);
    	  __first += __chunk_size;
    	}
          std::__insertion_sort(__first, __last, __comp);
        }
    
      enum { _S_chunk_size = 7 };
    
      template<typename _RandomAccessIterator, typename _Pointer>
        void
        __merge_sort_with_buffer(_RandomAccessIterator __first,
    			     _RandomAccessIterator __last,
                                 _Pointer __buffer)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::difference_type
    	_Distance;
    
          const _Distance __len = __last - __first;
          const _Pointer __buffer_last = __buffer + __len;
    
          _Distance __step_size = _S_chunk_size;
          std::__chunk_insertion_sort(__first, __last, __step_size);
    
          while (__step_size < __len)
    	{
    	  std::__merge_sort_loop(__first, __last, __buffer, __step_size);
    	  __step_size *= 2;
    	  std::__merge_sort_loop(__buffer, __buffer_last, __first, __step_size);
    	  __step_size *= 2;
    	}
        }
    
      template<typename _RandomAccessIterator, typename _Pointer, typename _Compare>
        void
        __merge_sort_with_buffer(_RandomAccessIterator __first,
    			     _RandomAccessIterator __last,
                                 _Pointer __buffer, _Compare __comp)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::difference_type
    	_Distance;
    
          const _Distance __len = __last - __first;
          const _Pointer __buffer_last = __buffer + __len;
    
          _Distance __step_size = _S_chunk_size;
          std::__chunk_insertion_sort(__first, __last, __step_size, __comp);
    
          while (__step_size < __len)
    	{
    	  std::__merge_sort_loop(__first, __last, __buffer,
    				 __step_size, __comp);
    	  __step_size *= 2;
    	  std::__merge_sort_loop(__buffer, __buffer_last, __first,
    				 __step_size, __comp);
    	  __step_size *= 2;
    	}
        }
    
      template<typename _RandomAccessIterator, typename _Pointer,
    	   typename _Distance>
        void
        __stable_sort_adaptive(_RandomAccessIterator __first,
    			   _RandomAccessIterator __last,
                               _Pointer __buffer, _Distance __buffer_size)
        {
          const _Distance __len = (__last - __first + 1) / 2;
          const _RandomAccessIterator __middle = __first + __len;
          if (__len > __buffer_size)
    	{
    	  std::__stable_sort_adaptive(__first, __middle,
    				      __buffer, __buffer_size);
    	  std::__stable_sort_adaptive(__middle, __last,
    				      __buffer, __buffer_size);
    	}
          else
    	{
    	  std::__merge_sort_with_buffer(__first, __middle, __buffer);
    	  std::__merge_sort_with_buffer(__middle, __last, __buffer);
    	}
          std::__merge_adaptive(__first, __middle, __last,
    			    _Distance(__middle - __first),
    			    _Distance(__last - __middle),
    			    __buffer, __buffer_size);
        }
    
      template<typename _RandomAccessIterator, typename _Pointer,
    	   typename _Distance, typename _Compare>
        void
        __stable_sort_adaptive(_RandomAccessIterator __first,
    			   _RandomAccessIterator __last,
                               _Pointer __buffer, _Distance __buffer_size,
                               _Compare __comp)
        {
          const _Distance __len = (__last - __first + 1) / 2;
          const _RandomAccessIterator __middle = __first + __len;
          if (__len > __buffer_size)
    	{
    	  std::__stable_sort_adaptive(__first, __middle, __buffer,
    				      __buffer_size, __comp);
    	  std::__stable_sort_adaptive(__middle, __last, __buffer,
    				      __buffer_size, __comp);
    	}
          else
    	{
    	  std::__merge_sort_with_buffer(__first, __middle, __buffer, __comp);
    	  std::__merge_sort_with_buffer(__middle, __last, __buffer, __comp);
    	}
          std::__merge_adaptive(__first, __middle, __last,
    			    _Distance(__middle - __first),
    			    _Distance(__last - __middle),
    			    __buffer, __buffer_size,
    			    __comp);
        }
    
      /// This is a helper function for the stable sorting routines.
      template<typename _RandomAccessIterator>
        void
        __inplace_stable_sort(_RandomAccessIterator __first,
    			  _RandomAccessIterator __last)
        {
          if (__last - __first < 15)
    	{
    	  std::__insertion_sort(__first, __last);
    	  return;
    	}
          _RandomAccessIterator __middle = __first + (__last - __first) / 2;
          std::__inplace_stable_sort(__first, __middle);
          std::__inplace_stable_sort(__middle, __last);
          std::__merge_without_buffer(__first, __middle, __last,
    				  __middle - __first,
    				  __last - __middle);
        }
    
      /// This is a helper function for the stable sorting routines.
      template<typename _RandomAccessIterator, typename _Compare>
        void
        __inplace_stable_sort(_RandomAccessIterator __first,
    			  _RandomAccessIterator __last, _Compare __comp)
        {
          if (__last - __first < 15)
    	{
    	  std::__insertion_sort(__first, __last, __comp);
    	  return;
    	}
          _RandomAccessIterator __middle = __first + (__last - __first) / 2;
          std::__inplace_stable_sort(__first, __middle, __comp);
          std::__inplace_stable_sort(__middle, __last, __comp);
          std::__merge_without_buffer(__first, __middle, __last,
    				  __middle - __first,
    				  __last - __middle,
    				  __comp);
        }
    
      // stable_sort
    
      // Set algorithms: includes, set_union, set_intersection, set_difference,
      // set_symmetric_difference.  All of these algorithms have the precondition
      // that their input ranges are sorted and the postcondition that their output
      // ranges are sorted.
    
      /**
       *  @brief Determines whether all elements of a sequence exists in a range.
       *  @param  __first1  Start of search range.
       *  @param  __last1   End of search range.
       *  @param  __first2  Start of sequence
       *  @param  __last2   End of sequence.
       *  @return  True if each element in [__first2,__last2) is contained in order
       *  within [__first1,__last1).  False otherwise.
       *  @ingroup set_algorithms
       *
       *  This operation expects both [__first1,__last1) and
       *  [__first2,__last2) to be sorted.  Searches for the presence of
       *  each element in [__first2,__last2) within [__first1,__last1).
       *  The iterators over each range only move forward, so this is a
       *  linear algorithm.  If an element in [__first2,__last2) is not
       *  found before the search iterator reaches @p __last2, false is
       *  returned.
      */
      template<typename _InputIterator1, typename _InputIterator2>
        bool
        includes(_InputIterator1 __first1, _InputIterator1 __last1,
    	     _InputIterator2 __first2, _InputIterator2 __last2)
        {
          typedef typename iterator_traits<_InputIterator1>::value_type
    	_ValueType1;
          typedef typename iterator_traits<_InputIterator2>::value_type
    	_ValueType2;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
          __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
          __glibcxx_requires_sorted_set(__first1, __last1, __first2);
          __glibcxx_requires_sorted_set(__first2, __last2, __first1);
    
          while (__first1 != __last1 && __first2 != __last2)
    	if (*__first2 < *__first1)
    	  return false;
    	else if(*__first1 < *__first2)
    	  ++__first1;
    	else
    	  ++__first1, ++__first2;
    
          return __first2 == __last2;
        }
    
      /**
       *  @brief Determines whether all elements of a sequence exists in a range
       *  using comparison.
       *  @ingroup set_algorithms
       *  @param  __first1  Start of search range.
       *  @param  __last1   End of search range.
       *  @param  __first2  Start of sequence
       *  @param  __last2   End of sequence.
       *  @param  __comp    Comparison function to use.
       *  @return True if each element in [__first2,__last2) is contained
       *  in order within [__first1,__last1) according to comp.  False
       *  otherwise.  @ingroup set_algorithms
       *
       *  This operation expects both [__first1,__last1) and
       *  [__first2,__last2) to be sorted.  Searches for the presence of
       *  each element in [__first2,__last2) within [__first1,__last1),
       *  using comp to decide.  The iterators over each range only move
       *  forward, so this is a linear algorithm.  If an element in
       *  [__first2,__last2) is not found before the search iterator
       *  reaches @p __last2, false is returned.
      */
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _Compare>
        bool
        includes(_InputIterator1 __first1, _InputIterator1 __last1,
    	     _InputIterator2 __first2, _InputIterator2 __last2,
    	     _Compare __comp)
        {
          typedef typename iterator_traits<_InputIterator1>::value_type
    	_ValueType1;
          typedef typename iterator_traits<_InputIterator2>::value_type
    	_ValueType2;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType1, _ValueType2>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType2, _ValueType1>)
          __glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
          __glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);
    
          while (__first1 != __last1 && __first2 != __last2)
    	if (__comp(*__first2, *__first1))
    	  return false;
    	else if(__comp(*__first1, *__first2))
    	  ++__first1;
    	else
    	  ++__first1, ++__first2;
    
          return __first2 == __last2;
        }
    
      // nth_element
      // merge
      // set_difference
      // set_intersection
      // set_union
      // stable_sort
      // set_symmetric_difference
      // min_element
      // max_element
    
      /**
       *  @brief  Permute range into the next @e dictionary ordering.
       *  @ingroup sorting_algorithms
       *  @param  __first  Start of range.
       *  @param  __last   End of range.
       *  @return  False if wrapped to first permutation, true otherwise.
       *
       *  Treats all permutations of the range as a set of @e dictionary sorted
       *  sequences.  Permutes the current sequence into the next one of this set.
       *  Returns true if there are more sequences to generate.  If the sequence
       *  is the largest of the set, the smallest is generated and false returned.
      */
      template<typename _BidirectionalIterator>
        bool
        next_permutation(_BidirectionalIterator __first,
    		     _BidirectionalIterator __last)
        {
          // concept requirements
          __glibcxx_function_requires(_BidirectionalIteratorConcept<
    				  _BidirectionalIterator>)
          __glibcxx_function_requires(_LessThanComparableConcept<
    	    typename iterator_traits<_BidirectionalIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return false;
          _BidirectionalIterator __i = __first;
          ++__i;
          if (__i == __last)
    	return false;
          __i = __last;
          --__i;
    
          for(;;)
    	{
    	  _BidirectionalIterator __ii = __i;
    	  --__i;
    	  if (*__i < *__ii)
    	    {
    	      _BidirectionalIterator __j = __last;
    	      while (!(*__i < *--__j))
    		{}
    	      std::iter_swap(__i, __j);
    	      std::reverse(__ii, __last);
    	      return true;
    	    }
    	  if (__i == __first)
    	    {
    	      std::reverse(__first, __last);
    	      return false;
    	    }
    	}
        }
    
      /**
       *  @brief  Permute range into the next @e dictionary ordering using
       *          comparison functor.
       *  @ingroup sorting_algorithms
       *  @param  __first  Start of range.
       *  @param  __last   End of range.
       *  @param  __comp   A comparison functor.
       *  @return  False if wrapped to first permutation, true otherwise.
       *
       *  Treats all permutations of the range [__first,__last) as a set of
       *  @e dictionary sorted sequences ordered by @p __comp.  Permutes the current
       *  sequence into the next one of this set.  Returns true if there are more
       *  sequences to generate.  If the sequence is the largest of the set, the
       *  smallest is generated and false returned.
      */
      template<typename _BidirectionalIterator, typename _Compare>
        bool
        next_permutation(_BidirectionalIterator __first,
    		     _BidirectionalIterator __last, _Compare __comp)
        {
          // concept requirements
          __glibcxx_function_requires(_BidirectionalIteratorConcept<
    				  _BidirectionalIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    	    typename iterator_traits<_BidirectionalIterator>::value_type,
    	    typename iterator_traits<_BidirectionalIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return false;
          _BidirectionalIterator __i = __first;
          ++__i;
          if (__i == __last)
    	return false;
          __i = __last;
          --__i;
    
          for(;;)
    	{
    	  _BidirectionalIterator __ii = __i;
    	  --__i;
    	  if (__comp(*__i, *__ii))
    	    {
    	      _BidirectionalIterator __j = __last;
    	      while (!bool(__comp(*__i, *--__j)))
    		{}
    	      std::iter_swap(__i, __j);
    	      std::reverse(__ii, __last);
    	      return true;
    	    }
    	  if (__i == __first)
    	    {
    	      std::reverse(__first, __last);
    	      return false;
    	    }
    	}
        }
    
      /**
       *  @brief  Permute range into the previous @e dictionary ordering.
       *  @ingroup sorting_algorithms
       *  @param  __first  Start of range.
       *  @param  __last   End of range.
       *  @return  False if wrapped to last permutation, true otherwise.
       *
       *  Treats all permutations of the range as a set of @e dictionary sorted
       *  sequences.  Permutes the current sequence into the previous one of this
       *  set.  Returns true if there are more sequences to generate.  If the
       *  sequence is the smallest of the set, the largest is generated and false
       *  returned.
      */
      template<typename _BidirectionalIterator>
        bool
        prev_permutation(_BidirectionalIterator __first,
    		     _BidirectionalIterator __last)
        {
          // concept requirements
          __glibcxx_function_requires(_BidirectionalIteratorConcept<
    				  _BidirectionalIterator>)
          __glibcxx_function_requires(_LessThanComparableConcept<
    	    typename iterator_traits<_BidirectionalIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return false;
          _BidirectionalIterator __i = __first;
          ++__i;
          if (__i == __last)
    	return false;
          __i = __last;
          --__i;
    
          for(;;)
    	{
    	  _BidirectionalIterator __ii = __i;
    	  --__i;
    	  if (*__ii < *__i)
    	    {
    	      _BidirectionalIterator __j = __last;
    	      while (!(*--__j < *__i))
    		{}
    	      std::iter_swap(__i, __j);
    	      std::reverse(__ii, __last);
    	      return true;
    	    }
    	  if (__i == __first)
    	    {
    	      std::reverse(__first, __last);
    	      return false;
    	    }
    	}
        }
    
      /**
       *  @brief  Permute range into the previous @e dictionary ordering using
       *          comparison functor.
       *  @ingroup sorting_algorithms
       *  @param  __first  Start of range.
       *  @param  __last   End of range.
       *  @param  __comp   A comparison functor.
       *  @return  False if wrapped to last permutation, true otherwise.
       *
       *  Treats all permutations of the range [__first,__last) as a set of
       *  @e dictionary sorted sequences ordered by @p __comp.  Permutes the current
       *  sequence into the previous one of this set.  Returns true if there are
       *  more sequences to generate.  If the sequence is the smallest of the set,
       *  the largest is generated and false returned.
      */
      template<typename _BidirectionalIterator, typename _Compare>
        bool
        prev_permutation(_BidirectionalIterator __first,
    		     _BidirectionalIterator __last, _Compare __comp)
        {
          // concept requirements
          __glibcxx_function_requires(_BidirectionalIteratorConcept<
    				  _BidirectionalIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    	    typename iterator_traits<_BidirectionalIterator>::value_type,
    	    typename iterator_traits<_BidirectionalIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return false;
          _BidirectionalIterator __i = __first;
          ++__i;
          if (__i == __last)
    	return false;
          __i = __last;
          --__i;
    
          for(;;)
    	{
    	  _BidirectionalIterator __ii = __i;
    	  --__i;
    	  if (__comp(*__ii, *__i))
    	    {
    	      _BidirectionalIterator __j = __last;
    	      while (!bool(__comp(*--__j, *__i)))
    		{}
    	      std::iter_swap(__i, __j);
    	      std::reverse(__ii, __last);
    	      return true;
    	    }
    	  if (__i == __first)
    	    {
    	      std::reverse(__first, __last);
    	      return false;
    	    }
    	}
        }
    
      // replace
      // replace_if
    
      /**
       *  @brief Copy a sequence, replacing each element of one value with another
       *         value.
       *  @param  __first      An input iterator.
       *  @param  __last       An input iterator.
       *  @param  __result     An output iterator.
       *  @param  __old_value  The value to be replaced.
       *  @param  __new_value  The replacement value.
       *  @return   The end of the output sequence, @p result+(last-first).
       *
       *  Copies each element in the input range @p [__first,__last) to the
       *  output range @p [__result,__result+(__last-__first)) replacing elements
       *  equal to @p __old_value with @p __new_value.
      */
      template<typename _InputIterator, typename _OutputIterator, typename _Tp>
        _OutputIterator
        replace_copy(_InputIterator __first, _InputIterator __last,
    		 _OutputIterator __result,
    		 const _Tp& __old_value, const _Tp& __new_value)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_function_requires(_EqualOpConcept<
    	    typename iterator_traits<_InputIterator>::value_type, _Tp>)
          __glibcxx_requires_valid_range(__first, __last);
    
          for (; __first != __last; ++__first, ++__result)
    	if (*__first == __old_value)
    	  *__result = __new_value;
    	else
    	  *__result = *__first;
          return __result;
        }
    
      /**
       *  @brief Copy a sequence, replacing each value for which a predicate
       *         returns true with another value.
       *  @ingroup mutating_algorithms
       *  @param  __first      An input iterator.
       *  @param  __last       An input iterator.
       *  @param  __result     An output iterator.
       *  @param  __pred       A predicate.
       *  @param  __new_value  The replacement value.
       *  @return   The end of the output sequence, @p __result+(__last-__first).
       *
       *  Copies each element in the range @p [__first,__last) to the range
       *  @p [__result,__result+(__last-__first)) replacing elements for which
       *  @p __pred returns true with @p __new_value.
      */
      template<typename _InputIterator, typename _OutputIterator,
    	   typename _Predicate, typename _Tp>
        _OutputIterator
        replace_copy_if(_InputIterator __first, _InputIterator __last,
    		    _OutputIterator __result,
    		    _Predicate __pred, const _Tp& __new_value)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          for (; __first != __last; ++__first, ++__result)
    	if (__pred(*__first))
    	  *__result = __new_value;
    	else
    	  *__result = *__first;
          return __result;
        }
    
    #ifdef __GXX_EXPERIMENTAL_CXX0X__
      /**
       *  @brief  Determines whether the elements of a sequence are sorted.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @return  True if the elements are sorted, false otherwise.
      */
      template<typename _ForwardIterator>
        inline bool
        is_sorted(_ForwardIterator __first, _ForwardIterator __last)
        { return std::is_sorted_until(__first, __last) == __last; }
    
      /**
       *  @brief  Determines whether the elements of a sequence are sorted
       *          according to a comparison functor.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __comp    A comparison functor.
       *  @return  True if the elements are sorted, false otherwise.
      */
      template<typename _ForwardIterator, typename _Compare>
        inline bool
        is_sorted(_ForwardIterator __first, _ForwardIterator __last,
    	      _Compare __comp)
        { return std::is_sorted_until(__first, __last, __comp) == __last; }
    
      /**
       *  @brief  Determines the end of a sorted sequence.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @return  An iterator pointing to the last iterator i in [__first, __last)
       *           for which the range [__first, i) is sorted.
      */
      template<typename _ForwardIterator>
        _ForwardIterator
        is_sorted_until(_ForwardIterator __first, _ForwardIterator __last)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_LessThanComparableConcept<
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return __last;
    
          _ForwardIterator __next = __first;
          for (++__next; __next != __last; __first = __next, ++__next)
    	if (*__next < *__first)
    	  return __next;
          return __next;
        }
    
      /**
       *  @brief  Determines the end of a sorted sequence using comparison functor.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __comp    A comparison functor.
       *  @return  An iterator pointing to the last iterator i in [__first, __last)
       *           for which the range [__first, i) is sorted.
      */
      template<typename _ForwardIterator, typename _Compare>
        _ForwardIterator
        is_sorted_until(_ForwardIterator __first, _ForwardIterator __last,
    		    _Compare __comp)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    	    typename iterator_traits<_ForwardIterator>::value_type,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return __last;
    
          _ForwardIterator __next = __first;
          for (++__next; __next != __last; __first = __next, ++__next)
    	if (__comp(*__next, *__first))
    	  return __next;
          return __next;
        }
    
      /**
       *  @brief  Determines min and max at once as an ordered pair.
       *  @ingroup sorting_algorithms
       *  @param  __a  A thing of arbitrary type.
       *  @param  __b  Another thing of arbitrary type.
       *  @return A pair(__b, __a) if __b is smaller than __a, pair(__a,
       *  __b) otherwise.
      */
      template<typename _Tp>
        inline pair<const _Tp&, const _Tp&>
        minmax(const _Tp& __a, const _Tp& __b)
        {
          // concept requirements
          __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
    
          return __b < __a ? pair<const _Tp&, const _Tp&>(__b, __a)
    	               : pair<const _Tp&, const _Tp&>(__a, __b);
        }
    
      /**
       *  @brief  Determines min and max at once as an ordered pair.
       *  @ingroup sorting_algorithms
       *  @param  __a  A thing of arbitrary type.
       *  @param  __b  Another thing of arbitrary type.
       *  @param  __comp  A @link comparison_functors comparison functor @endlink.
       *  @return A pair(__b, __a) if __b is smaller than __a, pair(__a,
       *  __b) otherwise.
      */
      template<typename _Tp, typename _Compare>
        inline pair<const _Tp&, const _Tp&>
        minmax(const _Tp& __a, const _Tp& __b, _Compare __comp)
        {
          return __comp(__b, __a) ? pair<const _Tp&, const _Tp&>(__b, __a)
    	                      : pair<const _Tp&, const _Tp&>(__a, __b);
        }
    
      /**
       *  @brief  Return a pair of iterators pointing to the minimum and maximum
       *          elements in a range.
       *  @ingroup sorting_algorithms
       *  @param  __first  Start of range.
       *  @param  __last   End of range.
       *  @return  make_pair(m, M), where m is the first iterator i in 
       *           [__first, __last) such that no other element in the range is
       *           smaller, and where M is the last iterator i in [__first, __last)
       *           such that no other element in the range is larger.
      */
      template<typename _ForwardIterator>
        pair<_ForwardIterator, _ForwardIterator>
        minmax_element(_ForwardIterator __first, _ForwardIterator __last)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_LessThanComparableConcept<
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          _ForwardIterator __next = __first;
          if (__first == __last
    	  || ++__next == __last)
    	return std::make_pair(__first, __first);
    
          _ForwardIterator __min, __max;
          if (*__next < *__first)
    	{
    	  __min = __next;
    	  __max = __first;
    	}
          else
    	{
    	  __min = __first;
    	  __max = __next;
    	}
    
          __first = __next;
          ++__first;
    
          while (__first != __last)
    	{
    	  __next = __first;
    	  if (++__next == __last)
    	    {
    	      if (*__first < *__min)
    		__min = __first;
    	      else if (!(*__first < *__max))
    		__max = __first;
    	      break;
    	    }
    
    	  if (*__next < *__first)
    	    {
    	      if (*__next < *__min)
    		__min = __next;
    	      if (!(*__first < *__max))
    		__max = __first;
    	    }
    	  else
    	    {
    	      if (*__first < *__min)
    		__min = __first;
    	      if (!(*__next < *__max))
    		__max = __next;
    	    }
    
    	  __first = __next;
    	  ++__first;
    	}
    
          return std::make_pair(__min, __max);
        }
    
      /**
       *  @brief  Return a pair of iterators pointing to the minimum and maximum
       *          elements in a range.
       *  @ingroup sorting_algorithms
       *  @param  __first  Start of range.
       *  @param  __last   End of range.
       *  @param  __comp   Comparison functor.
       *  @return  make_pair(m, M), where m is the first iterator i in 
       *           [__first, __last) such that no other element in the range is
       *           smaller, and where M is the last iterator i in [__first, __last)
       *           such that no other element in the range is larger.
      */
      template<typename _ForwardIterator, typename _Compare>
        pair<_ForwardIterator, _ForwardIterator>
        minmax_element(_ForwardIterator __first, _ForwardIterator __last,
    		   _Compare __comp)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    	    typename iterator_traits<_ForwardIterator>::value_type,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          _ForwardIterator __next = __first;
          if (__first == __last
    	  || ++__next == __last)
    	return std::make_pair(__first, __first);
    
          _ForwardIterator __min, __max;
          if (__comp(*__next, *__first))
    	{
    	  __min = __next;
    	  __max = __first;
    	}
          else
    	{
    	  __min = __first;
    	  __max = __next;
    	}
    
          __first = __next;
          ++__first;
    
          while (__first != __last)
    	{
    	  __next = __first;
    	  if (++__next == __last)
    	    {
    	      if (__comp(*__first, *__min))
    		__min = __first;
    	      else if (!__comp(*__first, *__max))
    		__max = __first;
    	      break;
    	    }
    
    	  if (__comp(*__next, *__first))
    	    {
    	      if (__comp(*__next, *__min))
    		__min = __next;
    	      if (!__comp(*__first, *__max))
    		__max = __first;
    	    }
    	  else
    	    {
    	      if (__comp(*__first, *__min))
    		__min = __first;
    	      if (!__comp(*__next, *__max))
    		__max = __next;
    	    }
    
    	  __first = __next;
    	  ++__first;
    	}
    
          return std::make_pair(__min, __max);
        }
    
      // N2722 + DR 915.
      template<typename _Tp>
        inline _Tp
        min(initializer_list<_Tp> __l)
        { return *std::min_element(__l.begin(), __l.end()); }
    
      template<typename _Tp, typename _Compare>
        inline _Tp
        min(initializer_list<_Tp> __l, _Compare __comp)
        { return *std::min_element(__l.begin(), __l.end(), __comp); }
    
      template<typename _Tp>
        inline _Tp
        max(initializer_list<_Tp> __l)
        { return *std::max_element(__l.begin(), __l.end()); }
    
      template<typename _Tp, typename _Compare>
        inline _Tp
        max(initializer_list<_Tp> __l, _Compare __comp)
        { return *std::max_element(__l.begin(), __l.end(), __comp); }
    
      template<typename _Tp>
        inline pair<_Tp, _Tp>
        minmax(initializer_list<_Tp> __l)
        {
          pair<const _Tp*, const _Tp*> __p =
    	std::minmax_element(__l.begin(), __l.end());
          return std::make_pair(*__p.first, *__p.second);
        }
    
      template<typename _Tp, typename _Compare>
        inline pair<_Tp, _Tp>
        minmax(initializer_list<_Tp> __l, _Compare __comp)
        {
          pair<const _Tp*, const _Tp*> __p =
    	std::minmax_element(__l.begin(), __l.end(), __comp);
          return std::make_pair(*__p.first, *__p.second);
        }
    
      /**
       *  @brief  Checks whether a permutaion of the second sequence is equal
       *          to the first sequence.
       *  @ingroup non_mutating_algorithms
       *  @param  __first1  Start of first range.
       *  @param  __last1   End of first range.
       *  @param  __first2  Start of second range.
       *  @return true if there exists a permutation of the elements in the range
       *          [__first2, __first2 + (__last1 - __first1)), beginning with 
       *          ForwardIterator2 begin, such that equal(__first1, __last1, begin)
       *          returns true; otherwise, returns false.
      */
      template<typename _ForwardIterator1, typename _ForwardIterator2>
        bool
        is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
    		   _ForwardIterator2 __first2)
        {
          // Efficiently compare identical prefixes:  O(N) if sequences
          // have the same elements in the same order.
          for (; __first1 != __last1; ++__first1, ++__first2)
    	if (!(*__first1 == *__first2))
    	  break;
    
          if (__first1 == __last1)
    	return true;
    
          // Establish __last2 assuming equal ranges by iterating over the
          // rest of the list.
          _ForwardIterator2 __last2 = __first2;
          std::advance(__last2, std::distance(__first1, __last1));
          for (_ForwardIterator1 __scan = __first1; __scan != __last1; ++__scan)
    	{
    	  if (__scan != _GLIBCXX_STD_A::find(__first1, __scan, *__scan))
    	    continue; // We've seen this one before.
    
    	  auto __matches = std::count(__first2, __last2, *__scan);
    	  if (0 == __matches
    	      || std::count(__scan, __last1, *__scan) != __matches)
    	    return false;
    	}
          return true;
        }
    
      /**
       *  @brief  Checks whether a permutation of the second sequence is equal
       *          to the first sequence.
       *  @ingroup non_mutating_algorithms
       *  @param  __first1  Start of first range.
       *  @param  __last1   End of first range.
       *  @param  __first2  Start of second range.
       *  @param  __pred    A binary predicate.
       *  @return true if there exists a permutation of the elements in
       *          the range [__first2, __first2 + (__last1 - __first1)),
       *          beginning with ForwardIterator2 begin, such that
       *          equal(__first1, __last1, __begin, __pred) returns true;
       *          otherwise, returns false.
      */
      template<typename _ForwardIterator1, typename _ForwardIterator2,
    	   typename _BinaryPredicate>
        bool
        is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
    		   _ForwardIterator2 __first2, _BinaryPredicate __pred)
        {
          // Efficiently compare identical prefixes:  O(N) if sequences
          // have the same elements in the same order.
          for (; __first1 != __last1; ++__first1, ++__first2)
    	if (!bool(__pred(*__first1, *__first2)))
    	  break;
    
          if (__first1 == __last1)
    	return true;
    
          // Establish __last2 assuming equal ranges by iterating over the
          // rest of the list.
          _ForwardIterator2 __last2 = __first2;
          std::advance(__last2, std::distance(__first1, __last1));
          for (_ForwardIterator1 __scan = __first1; __scan != __last1; ++__scan)
    	{
    	  using std::placeholders::_1;
    
    	  if (__scan != _GLIBCXX_STD_A::find_if(__first1, __scan,
    						std::bind(__pred, _1, *__scan)))
    	    continue; // We've seen this one before.
    	  
    	  auto __matches = std::count_if(__first2, __last2,
    					 std::bind(__pred, _1, *__scan));
    	  if (0 == __matches
    	      || std::count_if(__scan, __last1,
    			       std::bind(__pred, _1, *__scan)) != __matches)
    	    return false;
    	}
          return true;
        }
    
    #ifdef _GLIBCXX_USE_C99_STDINT_TR1
      /**
       *  @brief Shuffle the elements of a sequence using a uniform random
       *         number generator.
       *  @ingroup mutating_algorithms
       *  @param  __first   A forward iterator.
       *  @param  __last    A forward iterator.
       *  @param  __g       A UniformRandomNumberGenerator (26.5.1.3).
       *  @return  Nothing.
       *
       *  Reorders the elements in the range @p [__first,__last) using @p __g to
       *  provide random numbers.
      */
      template<typename _RandomAccessIterator,
    	   typename _UniformRandomNumberGenerator>
        void
        shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
    	    _UniformRandomNumberGenerator&& __g)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    	    _RandomAccessIterator>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return;
    
          typedef typename iterator_traits<_RandomAccessIterator>::difference_type
    	_DistanceType;
    
          typedef typename std::make_unsigned<_DistanceType>::type __ud_type;
          typedef typename std::uniform_int_distribution<__ud_type> __distr_type;
          typedef typename __distr_type::param_type __p_type;
          __distr_type __d;
    
          for (_RandomAccessIterator __i = __first + 1; __i != __last; ++__i)
    	std::iter_swap(__i, __first + __d(__g, __p_type(0, __i - __first)));
        }
    #endif
    
    #endif // __GXX_EXPERIMENTAL_CXX0X__
    
    _GLIBCXX_END_NAMESPACE_VERSION
    
    _GLIBCXX_BEGIN_NAMESPACE_ALGO
    
      /**
       *  @brief Apply a function to every element of a sequence.
       *  @ingroup non_mutating_algorithms
       *  @param  __first  An input iterator.
       *  @param  __last   An input iterator.
       *  @param  __f      A unary function object.
       *  @return   @p __f (std::move(@p __f) in C++0x).
       *
       *  Applies the function object @p __f to each element in the range
       *  @p [first,last).  @p __f must not modify the order of the sequence.
       *  If @p __f has a return value it is ignored.
      */
      template<typename _InputIterator, typename _Function>
        _Function
        for_each(_InputIterator __first, _InputIterator __last, _Function __f)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_requires_valid_range(__first, __last);
          for (; __first != __last; ++__first)
    	__f(*__first);
          return _GLIBCXX_MOVE(__f);
        }
    
      /**
       *  @brief Find the first occurrence of a value in a sequence.
       *  @ingroup non_mutating_algorithms
       *  @param  __first  An input iterator.
       *  @param  __last   An input iterator.
       *  @param  __val    The value to find.
       *  @return   The first iterator @c i in the range @p [__first,__last)
       *  such that @c *i == @p __val, or @p __last if no such iterator exists.
      */
      template<typename _InputIterator, typename _Tp>
        inline _InputIterator
        find(_InputIterator __first, _InputIterator __last,
    	 const _Tp& __val)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_EqualOpConcept<
    		typename iterator_traits<_InputIterator>::value_type, _Tp>)
          __glibcxx_requires_valid_range(__first, __last);
          return std::__find(__first, __last, __val,
    		         std::__iterator_category(__first));
        }
    
      /**
       *  @brief Find the first element in a sequence for which a
       *         predicate is true.
       *  @ingroup non_mutating_algorithms
       *  @param  __first  An input iterator.
       *  @param  __last   An input iterator.
       *  @param  __pred   A predicate.
       *  @return   The first iterator @c i in the range @p [__first,__last)
       *  such that @p __pred(*i) is true, or @p __last if no such iterator exists.
      */
      template<typename _InputIterator, typename _Predicate>
        inline _InputIterator
        find_if(_InputIterator __first, _InputIterator __last,
    	    _Predicate __pred)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    	      typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
          return std::__find_if(__first, __last, __pred,
    			    std::__iterator_category(__first));
        }
    
      /**
       *  @brief  Find element from a set in a sequence.
       *  @ingroup non_mutating_algorithms
       *  @param  __first1  Start of range to search.
       *  @param  __last1   End of range to search.
       *  @param  __first2  Start of match candidates.
       *  @param  __last2   End of match candidates.
       *  @return   The first iterator @c i in the range
       *  @p [__first1,__last1) such that @c *i == @p *(i2) such that i2 is an
       *  iterator in [__first2,__last2), or @p __last1 if no such iterator exists.
       *
       *  Searches the range @p [__first1,__last1) for an element that is
       *  equal to some element in the range [__first2,__last2).  If
       *  found, returns an iterator in the range [__first1,__last1),
       *  otherwise returns @p __last1.
      */
      template<typename _InputIterator, typename _ForwardIterator>
        _InputIterator
        find_first_of(_InputIterator __first1, _InputIterator __last1,
    		  _ForwardIterator __first2, _ForwardIterator __last2)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_EqualOpConcept<
    	    typename iterator_traits<_InputIterator>::value_type,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first1, __last1);
          __glibcxx_requires_valid_range(__first2, __last2);
    
          for (; __first1 != __last1; ++__first1)
    	for (_ForwardIterator __iter = __first2; __iter != __last2; ++__iter)
    	  if (*__first1 == *__iter)
    	    return __first1;
          return __last1;
        }
    
      /**
       *  @brief  Find element from a set in a sequence using a predicate.
       *  @ingroup non_mutating_algorithms
       *  @param  __first1  Start of range to search.
       *  @param  __last1   End of range to search.
       *  @param  __first2  Start of match candidates.
       *  @param  __last2   End of match candidates.
       *  @param  __comp    Predicate to use.
       *  @return   The first iterator @c i in the range
       *  @p [__first1,__last1) such that @c comp(*i, @p *(i2)) is true
       *  and i2 is an iterator in [__first2,__last2), or @p __last1 if no
       *  such iterator exists.
       *
    
       *  Searches the range @p [__first1,__last1) for an element that is
       *  equal to some element in the range [__first2,__last2).  If
       *  found, returns an iterator in the range [__first1,__last1),
       *  otherwise returns @p __last1.
      */
      template<typename _InputIterator, typename _ForwardIterator,
    	   typename _BinaryPredicate>
        _InputIterator
        find_first_of(_InputIterator __first1, _InputIterator __last1,
    		  _ForwardIterator __first2, _ForwardIterator __last2,
    		  _BinaryPredicate __comp)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
    	    typename iterator_traits<_InputIterator>::value_type,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first1, __last1);
          __glibcxx_requires_valid_range(__first2, __last2);
    
          for (; __first1 != __last1; ++__first1)
    	for (_ForwardIterator __iter = __first2; __iter != __last2; ++__iter)
    	  if (__comp(*__first1, *__iter))
    	    return __first1;
          return __last1;
        }
    
      /**
       *  @brief Find two adjacent values in a sequence that are equal.
       *  @ingroup non_mutating_algorithms
       *  @param  __first  A forward iterator.
       *  @param  __last   A forward iterator.
       *  @return   The first iterator @c i such that @c i and @c i+1 are both
       *  valid iterators in @p [__first,__last) and such that @c *i == @c *(i+1),
       *  or @p __last if no such iterator exists.
      */
      template<typename _ForwardIterator>
        _ForwardIterator
        adjacent_find(_ForwardIterator __first, _ForwardIterator __last)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_EqualityComparableConcept<
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
          if (__first == __last)
    	return __last;
          _ForwardIterator __next = __first;
          while(++__next != __last)
    	{
    	  if (*__first == *__next)
    	    return __first;
    	  __first = __next;
    	}
          return __last;
        }
    
      /**
       *  @brief Find two adjacent values in a sequence using a predicate.
       *  @ingroup non_mutating_algorithms
       *  @param  __first         A forward iterator.
       *  @param  __last          A forward iterator.
       *  @param  __binary_pred   A binary predicate.
       *  @return   The first iterator @c i such that @c i and @c i+1 are both
       *  valid iterators in @p [__first,__last) and such that
       *  @p __binary_pred(*i,*(i+1)) is true, or @p __last if no such iterator
       *  exists.
      */
      template<typename _ForwardIterator, typename _BinaryPredicate>
        _ForwardIterator
        adjacent_find(_ForwardIterator __first, _ForwardIterator __last,
    		  _BinaryPredicate __binary_pred)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
    	    typename iterator_traits<_ForwardIterator>::value_type,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
          if (__first == __last)
    	return __last;
          _ForwardIterator __next = __first;
          while(++__next != __last)
    	{
    	  if (__binary_pred(*__first, *__next))
    	    return __first;
    	  __first = __next;
    	}
          return __last;
        }
    
      /**
       *  @brief Count the number of copies of a value in a sequence.
       *  @ingroup non_mutating_algorithms
       *  @param  __first  An input iterator.
       *  @param  __last   An input iterator.
       *  @param  __value  The value to be counted.
       *  @return   The number of iterators @c i in the range @p [__first,__last)
       *  for which @c *i == @p __value
      */
      template<typename _InputIterator, typename _Tp>
        typename iterator_traits<_InputIterator>::difference_type
        count(_InputIterator __first, _InputIterator __last, const _Tp& __value)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_EqualOpConcept<
    	typename iterator_traits<_InputIterator>::value_type, _Tp>)
          __glibcxx_requires_valid_range(__first, __last);
          typename iterator_traits<_InputIterator>::difference_type __n = 0;
          for (; __first != __last; ++__first)
    	if (*__first == __value)
    	  ++__n;
          return __n;
        }
    
      /**
       *  @brief Count the elements of a sequence for which a predicate is true.
       *  @ingroup non_mutating_algorithms
       *  @param  __first  An input iterator.
       *  @param  __last   An input iterator.
       *  @param  __pred   A predicate.
       *  @return   The number of iterators @c i in the range @p [__first,__last)
       *  for which @p __pred(*i) is true.
      */
      template<typename _InputIterator, typename _Predicate>
        typename iterator_traits<_InputIterator>::difference_type
        count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
          typename iterator_traits<_InputIterator>::difference_type __n = 0;
          for (; __first != __last; ++__first)
    	if (__pred(*__first))
    	  ++__n;
          return __n;
        }
    
      /**
       *  @brief Search a sequence for a matching sub-sequence.
       *  @ingroup non_mutating_algorithms
       *  @param  __first1  A forward iterator.
       *  @param  __last1   A forward iterator.
       *  @param  __first2  A forward iterator.
       *  @param  __last2   A forward iterator.
       *  @return The first iterator @c i in the range @p
       *  [__first1,__last1-(__last2-__first2)) such that @c *(i+N) == @p
       *  *(__first2+N) for each @c N in the range @p
       *  [0,__last2-__first2), or @p __last1 if no such iterator exists.
       *
       *  Searches the range @p [__first1,__last1) for a sub-sequence that
       *  compares equal value-by-value with the sequence given by @p
       *  [__first2,__last2) and returns an iterator to the first element
       *  of the sub-sequence, or @p __last1 if the sub-sequence is not
       *  found.
       *
       *  Because the sub-sequence must lie completely within the range @p
       *  [__first1,__last1) it must start at a position less than @p
       *  __last1-(__last2-__first2) where @p __last2-__first2 is the
       *  length of the sub-sequence.
       *
       *  This means that the returned iterator @c i will be in the range
       *  @p [__first1,__last1-(__last2-__first2))
      */
      template<typename _ForwardIterator1, typename _ForwardIterator2>
        _ForwardIterator1
        search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
    	   _ForwardIterator2 __first2, _ForwardIterator2 __last2)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
          __glibcxx_function_requires(_EqualOpConcept<
    	    typename iterator_traits<_ForwardIterator1>::value_type,
    	    typename iterator_traits<_ForwardIterator2>::value_type>)
          __glibcxx_requires_valid_range(__first1, __last1);
          __glibcxx_requires_valid_range(__first2, __last2);
    
          // Test for empty ranges
          if (__first1 == __last1 || __first2 == __last2)
    	return __first1;
    
          // Test for a pattern of length 1.
          _ForwardIterator2 __p1(__first2);
          if (++__p1 == __last2)
    	return _GLIBCXX_STD_A::find(__first1, __last1, *__first2);
    
          // General case.
          _ForwardIterator2 __p;
          _ForwardIterator1 __current = __first1;
    
          for (;;)
    	{
    	  __first1 = _GLIBCXX_STD_A::find(__first1, __last1, *__first2);
    	  if (__first1 == __last1)
    	    return __last1;
    
    	  __p = __p1;
    	  __current = __first1;
    	  if (++__current == __last1)
    	    return __last1;
    
    	  while (*__current == *__p)
    	    {
    	      if (++__p == __last2)
    		return __first1;
    	      if (++__current == __last1)
    		return __last1;
    	    }
    	  ++__first1;
    	}
          return __first1;
        }
    
      /**
       *  @brief Search a sequence for a matching sub-sequence using a predicate.
       *  @ingroup non_mutating_algorithms
       *  @param  __first1     A forward iterator.
       *  @param  __last1      A forward iterator.
       *  @param  __first2     A forward iterator.
       *  @param  __last2      A forward iterator.
       *  @param  __predicate  A binary predicate.
       *  @return   The first iterator @c i in the range
       *  @p [__first1,__last1-(__last2-__first2)) such that
       *  @p __predicate(*(i+N),*(__first2+N)) is true for each @c N in the range
       *  @p [0,__last2-__first2), or @p __last1 if no such iterator exists.
       *
       *  Searches the range @p [__first1,__last1) for a sub-sequence that
       *  compares equal value-by-value with the sequence given by @p
       *  [__first2,__last2), using @p __predicate to determine equality,
       *  and returns an iterator to the first element of the
       *  sub-sequence, or @p __last1 if no such iterator exists.
       *
       *  @see search(_ForwardIter1, _ForwardIter1, _ForwardIter2, _ForwardIter2)
      */
      template<typename _ForwardIterator1, typename _ForwardIterator2,
    	   typename _BinaryPredicate>
        _ForwardIterator1
        search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
    	   _ForwardIterator2 __first2, _ForwardIterator2 __last2,
    	   _BinaryPredicate  __predicate)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
    	    typename iterator_traits<_ForwardIterator1>::value_type,
    	    typename iterator_traits<_ForwardIterator2>::value_type>)
          __glibcxx_requires_valid_range(__first1, __last1);
          __glibcxx_requires_valid_range(__first2, __last2);
    
          // Test for empty ranges
          if (__first1 == __last1 || __first2 == __last2)
    	return __first1;
    
          // Test for a pattern of length 1.
          _ForwardIterator2 __p1(__first2);
          if (++__p1 == __last2)
    	{
    	  while (__first1 != __last1
    		 && !bool(__predicate(*__first1, *__first2)))
    	    ++__first1;
    	  return __first1;
    	}
    
          // General case.
          _ForwardIterator2 __p;
          _ForwardIterator1 __current = __first1;
    
          for (;;)
    	{
    	  while (__first1 != __last1
    		 && !bool(__predicate(*__first1, *__first2)))
    	    ++__first1;
    	  if (__first1 == __last1)
    	    return __last1;
    
    	  __p = __p1;
    	  __current = __first1;
    	  if (++__current == __last1)
    	    return __last1;
    
    	  while (__predicate(*__current, *__p))
    	    {
    	      if (++__p == __last2)
    		return __first1;
    	      if (++__current == __last1)
    		return __last1;
    	    }
    	  ++__first1;
    	}
          return __first1;
        }
    
    
      /**
       *  @brief Search a sequence for a number of consecutive values.
       *  @ingroup non_mutating_algorithms
       *  @param  __first  A forward iterator.
       *  @param  __last   A forward iterator.
       *  @param  __count  The number of consecutive values.
       *  @param  __val    The value to find.
       *  @return The first iterator @c i in the range @p
       *  [__first,__last-__count) such that @c *(i+N) == @p __val for
       *  each @c N in the range @p [0,__count), or @p __last if no such
       *  iterator exists.
       *
       *  Searches the range @p [__first,__last) for @p count consecutive elements
       *  equal to @p __val.
      */
      template<typename _ForwardIterator, typename _Integer, typename _Tp>
        _ForwardIterator
        search_n(_ForwardIterator __first, _ForwardIterator __last,
    	     _Integer __count, const _Tp& __val)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_EqualOpConcept<
    	typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__count <= 0)
    	return __first;
          if (__count == 1)
    	return _GLIBCXX_STD_A::find(__first, __last, __val);
          return std::__search_n(__first, __last, __count, __val,
    			     std::__iterator_category(__first));
        }
    
    
      /**
       *  @brief Search a sequence for a number of consecutive values using a
       *         predicate.
       *  @ingroup non_mutating_algorithms
       *  @param  __first        A forward iterator.
       *  @param  __last         A forward iterator.
       *  @param  __count        The number of consecutive values.
       *  @param  __val          The value to find.
       *  @param  __binary_pred  A binary predicate.
       *  @return The first iterator @c i in the range @p
       *  [__first,__last-__count) such that @p
       *  __binary_pred(*(i+N),__val) is true for each @c N in the range
       *  @p [0,__count), or @p __last if no such iterator exists.
       *
       *  Searches the range @p [__first,__last) for @p __count
       *  consecutive elements for which the predicate returns true.
      */
      template<typename _ForwardIterator, typename _Integer, typename _Tp,
               typename _BinaryPredicate>
        _ForwardIterator
        search_n(_ForwardIterator __first, _ForwardIterator __last,
    	     _Integer __count, const _Tp& __val,
    	     _BinaryPredicate __binary_pred)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
    	    typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__count <= 0)
    	return __first;
          if (__count == 1)
    	{
    	  while (__first != __last && !bool(__binary_pred(*__first, __val)))
    	    ++__first;
    	  return __first;
    	}
          return std::__search_n(__first, __last, __count, __val, __binary_pred,
    			     std::__iterator_category(__first));
        }
    
    
      /**
       *  @brief Perform an operation on a sequence.
       *  @ingroup mutating_algorithms
       *  @param  __first     An input iterator.
       *  @param  __last      An input iterator.
       *  @param  __result    An output iterator.
       *  @param  __unary_op  A unary operator.
       *  @return   An output iterator equal to @p __result+(__last-__first).
       *
       *  Applies the operator to each element in the input range and assigns
       *  the results to successive elements of the output sequence.
       *  Evaluates @p *(__result+N)=unary_op(*(__first+N)) for each @c N in the
       *  range @p [0,__last-__first).
       *
       *  @p unary_op must not alter its argument.
      */
      template<typename _InputIterator, typename _OutputIterator,
    	   typename _UnaryOperation>
        _OutputIterator
        transform(_InputIterator __first, _InputIterator __last,
    	      _OutputIterator __result, _UnaryOperation __unary_op)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
                // "the type returned by a _UnaryOperation"
                __typeof__(__unary_op(*__first))>)
          __glibcxx_requires_valid_range(__first, __last);
    
          for (; __first != __last; ++__first, ++__result)
    	*__result = __unary_op(*__first);
          return __result;
        }
    
      /**
       *  @brief Perform an operation on corresponding elements of two sequences.
       *  @ingroup mutating_algorithms
       *  @param  __first1     An input iterator.
       *  @param  __last1      An input iterator.
       *  @param  __first2     An input iterator.
       *  @param  __result     An output iterator.
       *  @param  __binary_op  A binary operator.
       *  @return   An output iterator equal to @p result+(last-first).
       *
       *  Applies the operator to the corresponding elements in the two
       *  input ranges and assigns the results to successive elements of the
       *  output sequence.
       *  Evaluates @p
       *  *(__result+N)=__binary_op(*(__first1+N),*(__first2+N)) for each
       *  @c N in the range @p [0,__last1-__first1).
       *
       *  @p binary_op must not alter either of its arguments.
      */
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator, typename _BinaryOperation>
        _OutputIterator
        transform(_InputIterator1 __first1, _InputIterator1 __last1,
    	      _InputIterator2 __first2, _OutputIterator __result,
    	      _BinaryOperation __binary_op)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
                // "the type returned by a _BinaryOperation"
                __typeof__(__binary_op(*__first1,*__first2))>)
          __glibcxx_requires_valid_range(__first1, __last1);
    
          for (; __first1 != __last1; ++__first1, ++__first2, ++__result)
    	*__result = __binary_op(*__first1, *__first2);
          return __result;
        }
    
      /**
       *  @brief Replace each occurrence of one value in a sequence with another
       *         value.
       *  @ingroup mutating_algorithms
       *  @param  __first      A forward iterator.
       *  @param  __last       A forward iterator.
       *  @param  __old_value  The value to be replaced.
       *  @param  __new_value  The replacement value.
       *  @return   replace() returns no value.
       *
       *  For each iterator @c i in the range @p [__first,__last) if @c *i ==
       *  @p __old_value then the assignment @c *i = @p __new_value is performed.
      */
      template<typename _ForwardIterator, typename _Tp>
        void
        replace(_ForwardIterator __first, _ForwardIterator __last,
    	    const _Tp& __old_value, const _Tp& __new_value)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
    				  _ForwardIterator>)
          __glibcxx_function_requires(_EqualOpConcept<
    	    typename iterator_traits<_ForwardIterator>::value_type, _Tp>)
          __glibcxx_function_requires(_ConvertibleConcept<_Tp,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          for (; __first != __last; ++__first)
    	if (*__first == __old_value)
    	  *__first = __new_value;
        }
    
      /**
       *  @brief Replace each value in a sequence for which a predicate returns
       *         true with another value.
       *  @ingroup mutating_algorithms
       *  @param  __first      A forward iterator.
       *  @param  __last       A forward iterator.
       *  @param  __pred       A predicate.
       *  @param  __new_value  The replacement value.
       *  @return   replace_if() returns no value.
       *
       *  For each iterator @c i in the range @p [__first,__last) if @p __pred(*i)
       *  is true then the assignment @c *i = @p __new_value is performed.
      */
      template<typename _ForwardIterator, typename _Predicate, typename _Tp>
        void
        replace_if(_ForwardIterator __first, _ForwardIterator __last,
    	       _Predicate __pred, const _Tp& __new_value)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
    				  _ForwardIterator>)
          __glibcxx_function_requires(_ConvertibleConcept<_Tp,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          for (; __first != __last; ++__first)
    	if (__pred(*__first))
    	  *__first = __new_value;
        }
    
      /**
       *  @brief Assign the result of a function object to each value in a
       *         sequence.
       *  @ingroup mutating_algorithms
       *  @param  __first  A forward iterator.
       *  @param  __last   A forward iterator.
       *  @param  __gen    A function object taking no arguments and returning
       *                 std::iterator_traits<_ForwardIterator>::value_type
       *  @return   generate() returns no value.
       *
       *  Performs the assignment @c *i = @p __gen() for each @c i in the range
       *  @p [__first,__last).
      */
      template<typename _ForwardIterator, typename _Generator>
        void
        generate(_ForwardIterator __first, _ForwardIterator __last,
    	     _Generator __gen)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_GeneratorConcept<_Generator,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          for (; __first != __last; ++__first)
    	*__first = __gen();
        }
    
      /**
       *  @brief Assign the result of a function object to each value in a
       *         sequence.
       *  @ingroup mutating_algorithms
       *  @param  __first  A forward iterator.
       *  @param  __n      The length of the sequence.
       *  @param  __gen    A function object taking no arguments and returning
       *                 std::iterator_traits<_ForwardIterator>::value_type
       *  @return   The end of the sequence, @p __first+__n
       *
       *  Performs the assignment @c *i = @p __gen() for each @c i in the range
       *  @p [__first,__first+__n).
       *
       *  _GLIBCXX_RESOLVE_LIB_DEFECTS
       *  DR 865. More algorithms that throw away information
      */
      template<typename _OutputIterator, typename _Size, typename _Generator>
        _OutputIterator
        generate_n(_OutputIterator __first, _Size __n, _Generator __gen)
        {
          // concept requirements
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
                // "the type returned by a _Generator"
                __typeof__(__gen())>)
    
          for (__decltype(__n + 0) __niter = __n;
    	   __niter > 0; --__niter, ++__first)
    	*__first = __gen();
          return __first;
        }
    
    
      /**
       *  @brief Copy a sequence, removing consecutive duplicate values.
       *  @ingroup mutating_algorithms
       *  @param  __first   An input iterator.
       *  @param  __last    An input iterator.
       *  @param  __result  An output iterator.
       *  @return   An iterator designating the end of the resulting sequence.
       *
       *  Copies each element in the range @p [__first,__last) to the range
       *  beginning at @p __result, except that only the first element is copied
       *  from groups of consecutive elements that compare equal.
       *  unique_copy() is stable, so the relative order of elements that are
       *  copied is unchanged.
       *
       *  _GLIBCXX_RESOLVE_LIB_DEFECTS
       *  DR 241. Does unique_copy() require CopyConstructible and Assignable?
       *  
       *  _GLIBCXX_RESOLVE_LIB_DEFECTS
       *  DR 538. 241 again: Does unique_copy() require CopyConstructible and 
       *  Assignable?
      */
      template<typename _InputIterator, typename _OutputIterator>
        inline _OutputIterator
        unique_copy(_InputIterator __first, _InputIterator __last,
    		_OutputIterator __result)
        {
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_function_requires(_EqualityComparableConcept<
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return __result;
          return std::__unique_copy(__first, __last, __result,
    				std::__iterator_category(__first),
    				std::__iterator_category(__result));
        }
    
      /**
       *  @brief Copy a sequence, removing consecutive values using a predicate.
       *  @ingroup mutating_algorithms
       *  @param  __first        An input iterator.
       *  @param  __last         An input iterator.
       *  @param  __result       An output iterator.
       *  @param  __binary_pred  A binary predicate.
       *  @return   An iterator designating the end of the resulting sequence.
       *
       *  Copies each element in the range @p [__first,__last) to the range
       *  beginning at @p __result, except that only the first element is copied
       *  from groups of consecutive elements for which @p __binary_pred returns
       *  true.
       *  unique_copy() is stable, so the relative order of elements that are
       *  copied is unchanged.
       *
       *  _GLIBCXX_RESOLVE_LIB_DEFECTS
       *  DR 241. Does unique_copy() require CopyConstructible and Assignable?
      */
      template<typename _InputIterator, typename _OutputIterator,
    	   typename _BinaryPredicate>
        inline _OutputIterator
        unique_copy(_InputIterator __first, _InputIterator __last,
    		_OutputIterator __result,
    		_BinaryPredicate __binary_pred)
        {
          // concept requirements -- predicates checked later
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    	    typename iterator_traits<_InputIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return __result;
          return std::__unique_copy(__first, __last, __result, __binary_pred,
    				std::__iterator_category(__first),
    				std::__iterator_category(__result));
        }
    
    
      /**
       *  @brief Randomly shuffle the elements of a sequence.
       *  @ingroup mutating_algorithms
       *  @param  __first   A forward iterator.
       *  @param  __last    A forward iterator.
       *  @return  Nothing.
       *
       *  Reorder the elements in the range @p [__first,__last) using a random
       *  distribution, so that every possible ordering of the sequence is
       *  equally likely.
      */
      template<typename _RandomAccessIterator>
        inline void
        random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    	    _RandomAccessIterator>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first != __last)
    	for (_RandomAccessIterator __i = __first + 1; __i != __last; ++__i)
    	  std::iter_swap(__i, __first + (std::rand() % ((__i - __first) + 1)));
        }
    
      /**
       *  @brief Shuffle the elements of a sequence using a random number
       *         generator.
       *  @ingroup mutating_algorithms
       *  @param  __first   A forward iterator.
       *  @param  __last    A forward iterator.
       *  @param  __rand    The RNG functor or function.
       *  @return  Nothing.
       *
       *  Reorders the elements in the range @p [__first,__last) using @p __rand to
       *  provide a random distribution. Calling @p __rand(N) for a positive
       *  integer @p N should return a randomly chosen integer from the
       *  range [0,N).
      */
      template<typename _RandomAccessIterator, typename _RandomNumberGenerator>
        void
        random_shuffle(_RandomAccessIterator __first, _RandomAccessIterator __last,
    #ifdef __GXX_EXPERIMENTAL_CXX0X__
    		   _RandomNumberGenerator&& __rand)
    #else
    		   _RandomNumberGenerator& __rand)
    #endif
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    	    _RandomAccessIterator>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return;
          for (_RandomAccessIterator __i = __first + 1; __i != __last; ++__i)
    	std::iter_swap(__i, __first + __rand((__i - __first) + 1));
        }
    
    
      /**
       *  @brief Move elements for which a predicate is true to the beginning
       *         of a sequence.
       *  @ingroup mutating_algorithms
       *  @param  __first   A forward iterator.
       *  @param  __last    A forward iterator.
       *  @param  __pred    A predicate functor.
       *  @return  An iterator @p middle such that @p __pred(i) is true for each
       *  iterator @p i in the range @p [__first,middle) and false for each @p i
       *  in the range @p [middle,__last).
       *
       *  @p __pred must not modify its operand. @p partition() does not preserve
       *  the relative ordering of elements in each group, use
       *  @p stable_partition() if this is needed.
      */
      template<typename _ForwardIterator, typename _Predicate>
        inline _ForwardIterator
        partition(_ForwardIterator __first, _ForwardIterator __last,
    	      _Predicate   __pred)
        {
          // concept requirements
          __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
    				  _ForwardIterator>)
          __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          return std::__partition(__first, __last, __pred,
    			      std::__iterator_category(__first));
        }
    
    
    
      /**
       *  @brief Sort the smallest elements of a sequence.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __middle  Another iterator.
       *  @param  __last    Another iterator.
       *  @return  Nothing.
       *
       *  Sorts the smallest @p (__middle-__first) elements in the range
       *  @p [first,last) and moves them to the range @p [__first,__middle). The
       *  order of the remaining elements in the range @p [__middle,__last) is
       *  undefined.
       *  After the sort if @e i and @e j are iterators in the range
       *  @p [__first,__middle) such that i precedes j and @e k is an iterator in
       *  the range @p [__middle,__last) then *j<*i and *k<*i are both false.
      */
      template<typename _RandomAccessIterator>
        inline void
        partial_sort(_RandomAccessIterator __first,
    		 _RandomAccessIterator __middle,
    		 _RandomAccessIterator __last)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
    
          // concept requirements
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    	    _RandomAccessIterator>)
          __glibcxx_function_requires(_LessThanComparableConcept<_ValueType>)
          __glibcxx_requires_valid_range(__first, __middle);
          __glibcxx_requires_valid_range(__middle, __last);
    
          std::__heap_select(__first, __middle, __last);
          std::sort_heap(__first, __middle);
        }
    
      /**
       *  @brief Sort the smallest elements of a sequence using a predicate
       *         for comparison.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __middle  Another iterator.
       *  @param  __last    Another iterator.
       *  @param  __comp    A comparison functor.
       *  @return  Nothing.
       *
       *  Sorts the smallest @p (__middle-__first) elements in the range
       *  @p [__first,__last) and moves them to the range @p [__first,__middle). The
       *  order of the remaining elements in the range @p [__middle,__last) is
       *  undefined.
       *  After the sort if @e i and @e j are iterators in the range
       *  @p [__first,__middle) such that i precedes j and @e k is an iterator in
       *  the range @p [__middle,__last) then @p *__comp(j,*i) and @p __comp(*k,*i)
       *  are both false.
      */
      template<typename _RandomAccessIterator, typename _Compare>
        inline void
        partial_sort(_RandomAccessIterator __first,
    		 _RandomAccessIterator __middle,
    		 _RandomAccessIterator __last,
    		 _Compare __comp)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
    
          // concept requirements
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    	    _RandomAccessIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType, _ValueType>)
          __glibcxx_requires_valid_range(__first, __middle);
          __glibcxx_requires_valid_range(__middle, __last);
    
          std::__heap_select(__first, __middle, __last, __comp);
          std::sort_heap(__first, __middle, __comp);
        }
    
      /**
       *  @brief Sort a sequence just enough to find a particular position.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __nth     Another iterator.
       *  @param  __last    Another iterator.
       *  @return  Nothing.
       *
       *  Rearranges the elements in the range @p [__first,__last) so that @p *__nth
       *  is the same element that would have been in that position had the
       *  whole sequence been sorted. The elements either side of @p *__nth are
       *  not completely sorted, but for any iterator @e i in the range
       *  @p [__first,__nth) and any iterator @e j in the range @p [__nth,__last) it
       *  holds that *j < *i is false.
      */
      template<typename _RandomAccessIterator>
        inline void
        nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth,
    		_RandomAccessIterator __last)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
    
          // concept requirements
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    				  _RandomAccessIterator>)
          __glibcxx_function_requires(_LessThanComparableConcept<_ValueType>)
          __glibcxx_requires_valid_range(__first, __nth);
          __glibcxx_requires_valid_range(__nth, __last);
    
          if (__first == __last || __nth == __last)
    	return;
    
          std::__introselect(__first, __nth, __last,
    			 std::__lg(__last - __first) * 2);
        }
    
      /**
       *  @brief Sort a sequence just enough to find a particular position
       *         using a predicate for comparison.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __nth     Another iterator.
       *  @param  __last    Another iterator.
       *  @param  __comp    A comparison functor.
       *  @return  Nothing.
       *
       *  Rearranges the elements in the range @p [__first,__last) so that @p *__nth
       *  is the same element that would have been in that position had the
       *  whole sequence been sorted. The elements either side of @p *__nth are
       *  not completely sorted, but for any iterator @e i in the range
       *  @p [__first,__nth) and any iterator @e j in the range @p [__nth,__last) it
       *  holds that @p __comp(*j,*i) is false.
      */
      template<typename _RandomAccessIterator, typename _Compare>
        inline void
        nth_element(_RandomAccessIterator __first, _RandomAccessIterator __nth,
    		_RandomAccessIterator __last, _Compare __comp)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
    
          // concept requirements
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    				  _RandomAccessIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType, _ValueType>)
          __glibcxx_requires_valid_range(__first, __nth);
          __glibcxx_requires_valid_range(__nth, __last);
    
          if (__first == __last || __nth == __last)
    	return;
    
          std::__introselect(__first, __nth, __last,
    			 std::__lg(__last - __first) * 2, __comp);
        }
    
    
      /**
       *  @brief Sort the elements of a sequence.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @return  Nothing.
       *
       *  Sorts the elements in the range @p [__first,__last) in ascending order,
       *  such that for each iterator @e i in the range @p [__first,__last-1),  
       *  *(i+1)<*i is false.
       *
       *  The relative ordering of equivalent elements is not preserved, use
       *  @p stable_sort() if this is needed.
      */
      template<typename _RandomAccessIterator>
        inline void
        sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
    
          // concept requirements
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    	    _RandomAccessIterator>)
          __glibcxx_function_requires(_LessThanComparableConcept<_ValueType>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first != __last)
    	{
    	  std::__introsort_loop(__first, __last,
    				std::__lg(__last - __first) * 2);
    	  std::__final_insertion_sort(__first, __last);
    	}
        }
    
      /**
       *  @brief Sort the elements of a sequence using a predicate for comparison.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __comp    A comparison functor.
       *  @return  Nothing.
       *
       *  Sorts the elements in the range @p [__first,__last) in ascending order,
       *  such that @p __comp(*(i+1),*i) is false for every iterator @e i in the
       *  range @p [__first,__last-1).
       *
       *  The relative ordering of equivalent elements is not preserved, use
       *  @p stable_sort() if this is needed.
      */
      template<typename _RandomAccessIterator, typename _Compare>
        inline void
        sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
    	 _Compare __comp)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
    
          // concept requirements
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    	    _RandomAccessIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare, _ValueType,
    				  _ValueType>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first != __last)
    	{
    	  std::__introsort_loop(__first, __last,
    				std::__lg(__last - __first) * 2, __comp);
    	  std::__final_insertion_sort(__first, __last, __comp);
    	}
        }
    
      /**
       *  @brief Merges two sorted ranges.
       *  @ingroup sorting_algorithms
       *  @param  __first1  An iterator.
       *  @param  __first2  Another iterator.
       *  @param  __last1   Another iterator.
       *  @param  __last2   Another iterator.
       *  @param  __result  An iterator pointing to the end of the merged range.
       *  @return         An iterator pointing to the first element <em>not less
       *                  than</em> @e val.
       *
       *  Merges the ranges @p [__first1,__last1) and @p [__first2,__last2) into
       *  the sorted range @p [__result, __result + (__last1-__first1) +
       *  (__last2-__first2)).  Both input ranges must be sorted, and the
       *  output range must not overlap with either of the input ranges.
       *  The sort is @e stable, that is, for equivalent elements in the
       *  two ranges, elements from the first range will always come
       *  before elements from the second.
      */
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator>
        _OutputIterator
        merge(_InputIterator1 __first1, _InputIterator1 __last1,
    	  _InputIterator2 __first2, _InputIterator2 __last2,
    	  _OutputIterator __result)
        {
          typedef typename iterator_traits<_InputIterator1>::value_type
    	_ValueType1;
          typedef typename iterator_traits<_InputIterator2>::value_type
    	_ValueType2;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType1>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType2>)
          __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)	
          __glibcxx_requires_sorted_set(__first1, __last1, __first2);
          __glibcxx_requires_sorted_set(__first2, __last2, __first1);
    
          while (__first1 != __last1 && __first2 != __last2)
    	{
    	  if (*__first2 < *__first1)
    	    {
    	      *__result = *__first2;
    	      ++__first2;
    	    }
    	  else
    	    {
    	      *__result = *__first1;
    	      ++__first1;
    	    }
    	  ++__result;
    	}
          return std::copy(__first2, __last2, std::copy(__first1, __last1,
    						    __result));
        }
    
      /**
       *  @brief Merges two sorted ranges.
       *  @ingroup sorting_algorithms
       *  @param  __first1  An iterator.
       *  @param  __first2  Another iterator.
       *  @param  __last1   Another iterator.
       *  @param  __last2   Another iterator.
       *  @param  __result  An iterator pointing to the end of the merged range.
       *  @param  __comp    A functor to use for comparisons.
       *  @return         An iterator pointing to the first element "not less
       *                  than" @e val.
       *
       *  Merges the ranges @p [__first1,__last1) and @p [__first2,__last2) into
       *  the sorted range @p [__result, __result + (__last1-__first1) +
       *  (__last2-__first2)).  Both input ranges must be sorted, and the
       *  output range must not overlap with either of the input ranges.
       *  The sort is @e stable, that is, for equivalent elements in the
       *  two ranges, elements from the first range will always come
       *  before elements from the second.
       *
       *  The comparison function should have the same effects on ordering as
       *  the function used for the initial sort.
      */
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator, typename _Compare>
        _OutputIterator
        merge(_InputIterator1 __first1, _InputIterator1 __last1,
    	  _InputIterator2 __first2, _InputIterator2 __last2,
    	  _OutputIterator __result, _Compare __comp)
        {
          typedef typename iterator_traits<_InputIterator1>::value_type
    	_ValueType1;
          typedef typename iterator_traits<_InputIterator2>::value_type
    	_ValueType2;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType1>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType2>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType2, _ValueType1>)
          __glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
          __glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);
    
          while (__first1 != __last1 && __first2 != __last2)
    	{
    	  if (__comp(*__first2, *__first1))
    	    {
    	      *__result = *__first2;
    	      ++__first2;
    	    }
    	  else
    	    {
    	      *__result = *__first1;
    	      ++__first1;
    	    }
    	  ++__result;
    	}
          return std::copy(__first2, __last2, std::copy(__first1, __last1,
    						    __result));
        }
    
    
      /**
       *  @brief Sort the elements of a sequence, preserving the relative order
       *         of equivalent elements.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @return  Nothing.
       *
       *  Sorts the elements in the range @p [__first,__last) in ascending order,
       *  such that for each iterator @p i in the range @p [__first,__last-1),
       *  @p *(i+1)<*i is false.
       *
       *  The relative ordering of equivalent elements is preserved, so any two
       *  elements @p x and @p y in the range @p [__first,__last) such that
       *  @p x<y is false and @p y<x is false will have the same relative
       *  ordering after calling @p stable_sort().
      */
      template<typename _RandomAccessIterator>
        inline void
        stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
          typedef typename iterator_traits<_RandomAccessIterator>::difference_type
    	_DistanceType;
    
          // concept requirements
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    	    _RandomAccessIterator>)
          __glibcxx_function_requires(_LessThanComparableConcept<_ValueType>)
          __glibcxx_requires_valid_range(__first, __last);
    
          _Temporary_buffer<_RandomAccessIterator, _ValueType> __buf(__first,
    								 __last);
          if (__buf.begin() == 0)
    	std::__inplace_stable_sort(__first, __last);
          else
    	std::__stable_sort_adaptive(__first, __last, __buf.begin(),
    				    _DistanceType(__buf.size()));
        }
    
      /**
       *  @brief Sort the elements of a sequence using a predicate for comparison,
       *         preserving the relative order of equivalent elements.
       *  @ingroup sorting_algorithms
       *  @param  __first   An iterator.
       *  @param  __last    Another iterator.
       *  @param  __comp    A comparison functor.
       *  @return  Nothing.
       *
       *  Sorts the elements in the range @p [__first,__last) in ascending order,
       *  such that for each iterator @p i in the range @p [__first,__last-1),
       *  @p __comp(*(i+1),*i) is false.
       *
       *  The relative ordering of equivalent elements is preserved, so any two
       *  elements @p x and @p y in the range @p [__first,__last) such that
       *  @p __comp(x,y) is false and @p __comp(y,x) is false will have the same
       *  relative ordering after calling @p stable_sort().
      */
      template<typename _RandomAccessIterator, typename _Compare>
        inline void
        stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
    		_Compare __comp)
        {
          typedef typename iterator_traits<_RandomAccessIterator>::value_type
    	_ValueType;
          typedef typename iterator_traits<_RandomAccessIterator>::difference_type
    	_DistanceType;
    
          // concept requirements
          __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    	    _RandomAccessIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType,
    				  _ValueType>)
          __glibcxx_requires_valid_range(__first, __last);
    
          _Temporary_buffer<_RandomAccessIterator, _ValueType> __buf(__first,
    								 __last);
          if (__buf.begin() == 0)
    	std::__inplace_stable_sort(__first, __last, __comp);
          else
    	std::__stable_sort_adaptive(__first, __last, __buf.begin(),
    				    _DistanceType(__buf.size()), __comp);
        }
    
    
      /**
       *  @brief Return the union of two sorted ranges.
       *  @ingroup set_algorithms
       *  @param  __first1  Start of first range.
       *  @param  __last1   End of first range.
       *  @param  __first2  Start of second range.
       *  @param  __last2   End of second range.
       *  @return  End of the output range.
       *  @ingroup set_algorithms
       *
       *  This operation iterates over both ranges, copying elements present in
       *  each range in order to the output range.  Iterators increment for each
       *  range.  When the current element of one range is less than the other,
       *  that element is copied and the iterator advanced.  If an element is
       *  contained in both ranges, the element from the first range is copied and
       *  both ranges advance.  The output range may not overlap either input
       *  range.
      */
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator>
        _OutputIterator
        set_union(_InputIterator1 __first1, _InputIterator1 __last1,
    	      _InputIterator2 __first2, _InputIterator2 __last2,
    	      _OutputIterator __result)
        {
          typedef typename iterator_traits<_InputIterator1>::value_type
    	_ValueType1;
          typedef typename iterator_traits<_InputIterator2>::value_type
    	_ValueType2;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType1>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType2>)
          __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
          __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
          __glibcxx_requires_sorted_set(__first1, __last1, __first2);
          __glibcxx_requires_sorted_set(__first2, __last2, __first1);
    
          while (__first1 != __last1 && __first2 != __last2)
    	{
    	  if (*__first1 < *__first2)
    	    {
    	      *__result = *__first1;
    	      ++__first1;
    	    }
    	  else if (*__first2 < *__first1)
    	    {
    	      *__result = *__first2;
    	      ++__first2;
    	    }
    	  else
    	    {
    	      *__result = *__first1;
    	      ++__first1;
    	      ++__first2;
    	    }
    	  ++__result;
    	}
          return std::copy(__first2, __last2, std::copy(__first1, __last1,
    						    __result));
        }
    
      /**
       *  @brief Return the union of two sorted ranges using a comparison functor.
       *  @ingroup set_algorithms
       *  @param  __first1  Start of first range.
       *  @param  __last1   End of first range.
       *  @param  __first2  Start of second range.
       *  @param  __last2   End of second range.
       *  @param  __comp    The comparison functor.
       *  @return  End of the output range.
       *  @ingroup set_algorithms
       *
       *  This operation iterates over both ranges, copying elements present in
       *  each range in order to the output range.  Iterators increment for each
       *  range.  When the current element of one range is less than the other
       *  according to @p __comp, that element is copied and the iterator advanced.
       *  If an equivalent element according to @p __comp is contained in both
       *  ranges, the element from the first range is copied and both ranges
       *  advance.  The output range may not overlap either input range.
      */
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator, typename _Compare>
        _OutputIterator
        set_union(_InputIterator1 __first1, _InputIterator1 __last1,
    	      _InputIterator2 __first2, _InputIterator2 __last2,
    	      _OutputIterator __result, _Compare __comp)
        {
          typedef typename iterator_traits<_InputIterator1>::value_type
    	_ValueType1;
          typedef typename iterator_traits<_InputIterator2>::value_type
    	_ValueType2;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType1>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType2>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType1, _ValueType2>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType2, _ValueType1>)
          __glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
          __glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);
    
          while (__first1 != __last1 && __first2 != __last2)
    	{
    	  if (__comp(*__first1, *__first2))
    	    {
    	      *__result = *__first1;
    	      ++__first1;
    	    }
    	  else if (__comp(*__first2, *__first1))
    	    {
    	      *__result = *__first2;
    	      ++__first2;
    	    }
    	  else
    	    {
    	      *__result = *__first1;
    	      ++__first1;
    	      ++__first2;
    	    }
    	  ++__result;
    	}
          return std::copy(__first2, __last2, std::copy(__first1, __last1,
    						    __result));
        }
    
      /**
       *  @brief Return the intersection of two sorted ranges.
       *  @ingroup set_algorithms
       *  @param  __first1  Start of first range.
       *  @param  __last1   End of first range.
       *  @param  __first2  Start of second range.
       *  @param  __last2   End of second range.
       *  @return  End of the output range.
       *  @ingroup set_algorithms
       *
       *  This operation iterates over both ranges, copying elements present in
       *  both ranges in order to the output range.  Iterators increment for each
       *  range.  When the current element of one range is less than the other,
       *  that iterator advances.  If an element is contained in both ranges, the
       *  element from the first range is copied and both ranges advance.  The
       *  output range may not overlap either input range.
      */
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator>
        _OutputIterator
        set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
    		     _InputIterator2 __first2, _InputIterator2 __last2,
    		     _OutputIterator __result)
        {
          typedef typename iterator_traits<_InputIterator1>::value_type
    	_ValueType1;
          typedef typename iterator_traits<_InputIterator2>::value_type
    	_ValueType2;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType1>)
          __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
          __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)
          __glibcxx_requires_sorted_set(__first1, __last1, __first2);
          __glibcxx_requires_sorted_set(__first2, __last2, __first1);
    
          while (__first1 != __last1 && __first2 != __last2)
    	if (*__first1 < *__first2)
    	  ++__first1;
    	else if (*__first2 < *__first1)
    	  ++__first2;
    	else
    	  {
    	    *__result = *__first1;
    	    ++__first1;
    	    ++__first2;
    	    ++__result;
    	  }
          return __result;
        }
    
      /**
       *  @brief Return the intersection of two sorted ranges using comparison
       *  functor.
       *  @ingroup set_algorithms
       *  @param  __first1  Start of first range.
       *  @param  __last1   End of first range.
       *  @param  __first2  Start of second range.
       *  @param  __last2   End of second range.
       *  @param  __comp    The comparison functor.
       *  @return  End of the output range.
       *  @ingroup set_algorithms
       *
       *  This operation iterates over both ranges, copying elements present in
       *  both ranges in order to the output range.  Iterators increment for each
       *  range.  When the current element of one range is less than the other
       *  according to @p __comp, that iterator advances.  If an element is
       *  contained in both ranges according to @p __comp, the element from the
       *  first range is copied and both ranges advance.  The output range may not
       *  overlap either input range.
      */
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator, typename _Compare>
        _OutputIterator
        set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
    		     _InputIterator2 __first2, _InputIterator2 __last2,
    		     _OutputIterator __result, _Compare __comp)
        {
          typedef typename iterator_traits<_InputIterator1>::value_type
    	_ValueType1;
          typedef typename iterator_traits<_InputIterator2>::value_type
    	_ValueType2;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType1>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType1, _ValueType2>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType2, _ValueType1>)
          __glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
          __glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);
    
          while (__first1 != __last1 && __first2 != __last2)
    	if (__comp(*__first1, *__first2))
    	  ++__first1;
    	else if (__comp(*__first2, *__first1))
    	  ++__first2;
    	else
    	  {
    	    *__result = *__first1;
    	    ++__first1;
    	    ++__first2;
    	    ++__result;
    	  }
          return __result;
        }
    
      /**
       *  @brief Return the difference of two sorted ranges.
       *  @ingroup set_algorithms
       *  @param  __first1  Start of first range.
       *  @param  __last1   End of first range.
       *  @param  __first2  Start of second range.
       *  @param  __last2   End of second range.
       *  @return  End of the output range.
       *  @ingroup set_algorithms
       *
       *  This operation iterates over both ranges, copying elements present in
       *  the first range but not the second in order to the output range.
       *  Iterators increment for each range.  When the current element of the
       *  first range is less than the second, that element is copied and the
       *  iterator advances.  If the current element of the second range is less,
       *  the iterator advances, but no element is copied.  If an element is
       *  contained in both ranges, no elements are copied and both ranges
       *  advance.  The output range may not overlap either input range.
      */
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator>
        _OutputIterator
        set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
    		   _InputIterator2 __first2, _InputIterator2 __last2,
    		   _OutputIterator __result)
        {
          typedef typename iterator_traits<_InputIterator1>::value_type
    	_ValueType1;
          typedef typename iterator_traits<_InputIterator2>::value_type
    	_ValueType2;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType1>)
          __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
          __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)	
          __glibcxx_requires_sorted_set(__first1, __last1, __first2);
          __glibcxx_requires_sorted_set(__first2, __last2, __first1);
    
          while (__first1 != __last1 && __first2 != __last2)
    	if (*__first1 < *__first2)
    	  {
    	    *__result = *__first1;
    	    ++__first1;
    	    ++__result;
    	  }
    	else if (*__first2 < *__first1)
    	  ++__first2;
    	else
    	  {
    	    ++__first1;
    	    ++__first2;
    	  }
          return std::copy(__first1, __last1, __result);
        }
    
      /**
       *  @brief  Return the difference of two sorted ranges using comparison
       *  functor.
       *  @ingroup set_algorithms
       *  @param  __first1  Start of first range.
       *  @param  __last1   End of first range.
       *  @param  __first2  Start of second range.
       *  @param  __last2   End of second range.
       *  @param  __comp    The comparison functor.
       *  @return  End of the output range.
       *  @ingroup set_algorithms
       *
       *  This operation iterates over both ranges, copying elements present in
       *  the first range but not the second in order to the output range.
       *  Iterators increment for each range.  When the current element of the
       *  first range is less than the second according to @p __comp, that element
       *  is copied and the iterator advances.  If the current element of the
       *  second range is less, no element is copied and the iterator advances.
       *  If an element is contained in both ranges according to @p __comp, no
       *  elements are copied and both ranges advance.  The output range may not
       *  overlap either input range.
      */
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator, typename _Compare>
        _OutputIterator
        set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
    		   _InputIterator2 __first2, _InputIterator2 __last2,
    		   _OutputIterator __result, _Compare __comp)
        {
          typedef typename iterator_traits<_InputIterator1>::value_type
    	_ValueType1;
          typedef typename iterator_traits<_InputIterator2>::value_type
    	_ValueType2;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType1>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType1, _ValueType2>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType2, _ValueType1>)
          __glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
          __glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);
    
          while (__first1 != __last1 && __first2 != __last2)
    	if (__comp(*__first1, *__first2))
    	  {
    	    *__result = *__first1;
    	    ++__first1;
    	    ++__result;
    	  }
    	else if (__comp(*__first2, *__first1))
    	  ++__first2;
    	else
    	  {
    	    ++__first1;
    	    ++__first2;
    	  }
          return std::copy(__first1, __last1, __result);
        }
    
      /**
       *  @brief  Return the symmetric difference of two sorted ranges.
       *  @ingroup set_algorithms
       *  @param  __first1  Start of first range.
       *  @param  __last1   End of first range.
       *  @param  __first2  Start of second range.
       *  @param  __last2   End of second range.
       *  @return  End of the output range.
       *  @ingroup set_algorithms
       *
       *  This operation iterates over both ranges, copying elements present in
       *  one range but not the other in order to the output range.  Iterators
       *  increment for each range.  When the current element of one range is less
       *  than the other, that element is copied and the iterator advances.  If an
       *  element is contained in both ranges, no elements are copied and both
       *  ranges advance.  The output range may not overlap either input range.
      */
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator>
        _OutputIterator
        set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
    			     _InputIterator2 __first2, _InputIterator2 __last2,
    			     _OutputIterator __result)
        {
          typedef typename iterator_traits<_InputIterator1>::value_type
    	_ValueType1;
          typedef typename iterator_traits<_InputIterator2>::value_type
    	_ValueType2;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType1>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType2>)
          __glibcxx_function_requires(_LessThanOpConcept<_ValueType1, _ValueType2>)
          __glibcxx_function_requires(_LessThanOpConcept<_ValueType2, _ValueType1>)	
          __glibcxx_requires_sorted_set(__first1, __last1, __first2);
          __glibcxx_requires_sorted_set(__first2, __last2, __first1);
    
          while (__first1 != __last1 && __first2 != __last2)
    	if (*__first1 < *__first2)
    	  {
    	    *__result = *__first1;
    	    ++__first1;
    	    ++__result;
    	  }
    	else if (*__first2 < *__first1)
    	  {
    	    *__result = *__first2;
    	    ++__first2;
    	    ++__result;
    	  }
    	else
    	  {
    	    ++__first1;
    	    ++__first2;
    	  }
          return std::copy(__first2, __last2, std::copy(__first1,
    						    __last1, __result));
        }
    
      /**
       *  @brief  Return the symmetric difference of two sorted ranges using
       *  comparison functor.
       *  @ingroup set_algorithms
       *  @param  __first1  Start of first range.
       *  @param  __last1   End of first range.
       *  @param  __first2  Start of second range.
       *  @param  __last2   End of second range.
       *  @param  __comp    The comparison functor.
       *  @return  End of the output range.
       *  @ingroup set_algorithms
       *
       *  This operation iterates over both ranges, copying elements present in
       *  one range but not the other in order to the output range.  Iterators
       *  increment for each range.  When the current element of one range is less
       *  than the other according to @p comp, that element is copied and the
       *  iterator advances.  If an element is contained in both ranges according
       *  to @p __comp, no elements are copied and both ranges advance.  The output
       *  range may not overlap either input range.
      */
      template<typename _InputIterator1, typename _InputIterator2,
    	   typename _OutputIterator, typename _Compare>
        _OutputIterator
        set_symmetric_difference(_InputIterator1 __first1, _InputIterator1 __last1,
    			     _InputIterator2 __first2, _InputIterator2 __last2,
    			     _OutputIterator __result,
    			     _Compare __comp)
        {
          typedef typename iterator_traits<_InputIterator1>::value_type
    	_ValueType1;
          typedef typename iterator_traits<_InputIterator2>::value_type
    	_ValueType2;
    
          // concept requirements
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
          __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType1>)
          __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    				  _ValueType2>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType1, _ValueType2>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    				  _ValueType2, _ValueType1>)
          __glibcxx_requires_sorted_set_pred(__first1, __last1, __first2, __comp);
          __glibcxx_requires_sorted_set_pred(__first2, __last2, __first1, __comp);
    
          while (__first1 != __last1 && __first2 != __last2)
    	if (__comp(*__first1, *__first2))
    	  {
    	    *__result = *__first1;
    	    ++__first1;
    	    ++__result;
    	  }
    	else if (__comp(*__first2, *__first1))
    	  {
    	    *__result = *__first2;
    	    ++__first2;
    	    ++__result;
    	  }
    	else
    	  {
    	    ++__first1;
    	    ++__first2;
    	  }
          return std::copy(__first2, __last2, 
    		       std::copy(__first1, __last1, __result));
        }
    
    
      /**
       *  @brief  Return the minimum element in a range.
       *  @ingroup sorting_algorithms
       *  @param  __first  Start of range.
       *  @param  __last   End of range.
       *  @return  Iterator referencing the first instance of the smallest value.
      */
      template<typename _ForwardIterator>
        _ForwardIterator
        min_element(_ForwardIterator __first, _ForwardIterator __last)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_LessThanComparableConcept<
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return __first;
          _ForwardIterator __result = __first;
          while (++__first != __last)
    	if (*__first < *__result)
    	  __result = __first;
          return __result;
        }
    
      /**
       *  @brief  Return the minimum element in a range using comparison functor.
       *  @ingroup sorting_algorithms
       *  @param  __first  Start of range.
       *  @param  __last   End of range.
       *  @param  __comp   Comparison functor.
       *  @return  Iterator referencing the first instance of the smallest value
       *  according to __comp.
      */
      template<typename _ForwardIterator, typename _Compare>
        _ForwardIterator
        min_element(_ForwardIterator __first, _ForwardIterator __last,
    		_Compare __comp)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    	    typename iterator_traits<_ForwardIterator>::value_type,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return __first;
          _ForwardIterator __result = __first;
          while (++__first != __last)
    	if (__comp(*__first, *__result))
    	  __result = __first;
          return __result;
        }
    
      /**
       *  @brief  Return the maximum element in a range.
       *  @ingroup sorting_algorithms
       *  @param  __first  Start of range.
       *  @param  __last   End of range.
       *  @return  Iterator referencing the first instance of the largest value.
      */
      template<typename _ForwardIterator>
        _ForwardIterator
        max_element(_ForwardIterator __first, _ForwardIterator __last)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_LessThanComparableConcept<
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last)
    	return __first;
          _ForwardIterator __result = __first;
          while (++__first != __last)
    	if (*__result < *__first)
    	  __result = __first;
          return __result;
        }
    
      /**
       *  @brief  Return the maximum element in a range using comparison functor.
       *  @ingroup sorting_algorithms
       *  @param  __first  Start of range.
       *  @param  __last   End of range.
       *  @param  __comp   Comparison functor.
       *  @return  Iterator referencing the first instance of the largest value
       *  according to __comp.
      */
      template<typename _ForwardIterator, typename _Compare>
        _ForwardIterator
        max_element(_ForwardIterator __first, _ForwardIterator __last,
    		_Compare __comp)
        {
          // concept requirements
          __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
          __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
    	    typename iterator_traits<_ForwardIterator>::value_type,
    	    typename iterator_traits<_ForwardIterator>::value_type>)
          __glibcxx_requires_valid_range(__first, __last);
    
          if (__first == __last) return __first;
          _ForwardIterator __result = __first;
          while (++__first != __last)
    	if (__comp(*__result, *__first))
    	  __result = __first;
          return __result;
        }
    
    _GLIBCXX_END_NAMESPACE_ALGO
    } // namespace std
    
    #endif /* _STL_ALGO_H */
    </span>

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  • 原文地址:https://www.cnblogs.com/gcczhongduan/p/5263415.html
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