数据结构：链表的操作

1 单链表翻转的非递归实现：

Node* reverse(Node *header)
    {
        Node* guard = NULL;//链表翻转后的头结点
        Node* current = reinterpret_cast<Node*>(header);//当前结点
        Node* prev = NULL;//前一结点
        while(current != NULL)
        {
            Node* pNext = current->next;//下一结点
            if(NULL == pNext)//如果是单结点链表
            {
                guard = current;
            }
            current->next = prev;//当前结点的下一个结点指向前一结点,实现翻转只需要更改这一个指向
            prev = current;//将前一结点移到当前结点位置（更新pre和current）
            current = pNext;//将当前结点后移
        }
        return guard;
    }

单链表的操作汇总

template <typename T>
  class LinkedList:public List<T>
  {
  protected:
    struct Node:public Object
    {
      T value;//数据域
      Node* next;//指针域
    };
    mutable struct:public Object
    {
      char reserved[sizeof(T)];//占位空间
      Node* next;
    }m_header;
    int m_length;
    int m_step;
    Node* m_current;
  protected:
    Node* position(int index)const
    {
      //指针指向头结点
      Node* ret = reinterpret_cast<Node*>(&m_header);
      //遍历到目标位置
      for(int i = 0; i < index; i++)
      {
          ret = ret->next;
      }
      return ret;
    }
  public:
    LinkedList()
    {
      m_header.next = NULL;
      m_length = 0;
      m_step = 1;
      m_current = NULL;
    }
    virtual ~LinkedList()
    {
      clear();
    }


/*

单链表的插入

*/

bool insert(int index, const T& value)
    {
      //判断目标位置是否合法
      bool ret = (0 <= index) && (index <= m_length);
      if(ret)
      {
          //创建新的结点
          Node* node = createNode();
          if(node != NULL)
          {
              //当前结点定位到目标位置
              Node* current = position(index);
              //修改插入结点的值
              node->value = value;
              //将当前位置的下一个结点作为插入结点的下一个结点
              node->next = current->next;
              //将要插入结点作为当前结点的下一个结点
              current->next = node;
              m_length++;//链表结点长度加1
          }
          else
          {
              THROW_EXCEPTION(NoEnoughMemoryException, "No enough memmory...");
          }
      }
      else
      {
          THROW_EXCEPTION(IndexOutOfBoudsException, "Parameter index is invalid...");
      }
      return ret;
    }
    bool insert(const T& value)
    {
      return insert(m_length, value);
    }


////////////////////////////
    bool remove(int index)
    {
      //判断目标位置是否合法
      bool ret = (0 <= index) && (index < m_length);
      if(ret)
      {
        //当前结点指向头结点
        Node* current = position(index);

        //使用toDel指向要删除的结点
        Node* toDel = current->next;
        //将当前结点的下一个结点指向要删除结点的下一个结点
        current->next = toDel->next;
        m_length--;//链表结点长度减1
        destroy(toDel);//释放要删除的结点的堆空间
      }
      else
      {
          THROW_EXCEPTION(IndexOutOfBoudsException, "Parameter inde is invalid...");
      }
      return ret;

    }


/////////
    bool set(int index, const T& value)
    {
      //判断目标位置是否合法
      bool ret = (0 <= index) && (index < m_length);
      if(ret)
      {
          //将当前结点指向头结点
          Node* current = position(index);

          //修改目标结点的数据域的值
          current->next->value = value;
      }
      else
      {
          THROW_EXCEPTION(IndexOutOfBoudsException, "Parameter inde is invalid...");
      }
      return ret;
    }



////////
    bool get(int index, T& value)const
    {
      //判断目标位置是否合法
      bool ret = (0 <= index) && (index < m_length);
      if(ret)
      {
          //当前结点指向头结点
          Node* current = position(index);
          //遍历到目标位置

          //获取目标结点的数据域的值
          value = current->next->value;
      }
      else
      {
          THROW_EXCEPTION(IndexOutOfBoudsException, "Parameter inde is invalid...");
      }
      return ret;
    }


    //重载版本
    T get(int index)const
    {
      T ret;
      if(get(index, ret))
        return ret;
    }
    int length()const
    {
      return m_length;
    }


///////////////
    int find(const T& value)const
    {
        int ret = -1;
        //指向头结点
        Node* node = m_header.next;
        int i = 0;
        while(node)
        {
            //找到元素，退出循环
            if(node->value == value)
            {
                ret = i;
                break;
            }
            else
            {
                node = node->next;
                 i++;
            }
        }
        return ret;
    }


//////////////
    void clear()
    {
      //遍历删除结点
      while(m_header.next)
      {
          //要删除的结点为头结点的下一个结点
          Node* toDel = m_header.next;
          //将头结点的下一个结点指向删除结点的下一个结点
          m_header.next = toDel->next;
          m_length--;
          destroy(toDel);//释放要删除结点

      }
    }


////////////
    bool move(int pos, int step = 1)
    {
      bool ret = (0 <= pos) && (pos < m_length) && (0 < step);
      if(ret)
      {
           m_current = position(pos)->next;
           m_step = step;
          }
      return ret;
    }


///////////////
    bool end()
    {
        return m_current == NULL;
    }
    T current()
    {
        if(!end())
        {
            return m_current->value;
        }
        else
        {
            THROW_EXCEPTION(InvalidOperationException, "Invalid Operation...");
        }
    }



////////////
    bool next()
    {
        int i = 0;
        while((i < m_step) && (!end()))
        {
            m_current = m_current->next;
            i++;
        }
        return (i == m_step);
    }
    virtual Node* createNode()
    {
        return new Node();
    }
    virtual void destroy(Node* node)
    {
        delete node;
    }
  };