算法-MergeSort

#include <iostream>
#include <vector>
#include <iterator>

using namespace std;

int COMPARE_COUNT = 0;

void merge_sort(vector<int> &array, vector<int> &aux, int lo, int hi)
{
if ( lo >= hi )
return;

int mid = ( hi + lo ) / 2;
merge_sort(array, aux, lo, mid);
merge_sort(array, aux, mid + 1, hi);

//vector<int> aux;
for ( int i = lo; i < hi +1; ++i )
aux[i] = array[i];

int i = lo;
int j = mid + 1;
int k = lo;

while ( k < hi + 1 )
{
if ( i > mid ) array[k++] = aux[j++];
else if ( j > hi ) array[k++] = aux[i++];
else if ( aux[i] <= aux[j] ) 
{
array[k++] = aux[i++];
COMPARE_COUNT++;
}
else{
array[k++] = aux[j++];
COMPARE_COUNT++;
}
}

return;
}

void Print(const vector<int> &array)
{
vector<int>::const_iterator _begin = array.begin();
while ( _begin != array.end() )
cout<<*_begin++<<" ";

cout<<endl;
}

int main()
{
cout<<"Please input the size of the array: ";
int size;
cin>>size;

vector<int> array;
for ( int i = 0; i < size; ++i )
array.push_back( rand() % size + 1);

cout<<"The shuffling array is:"<<endl;
Print(array);

vector<int> aux;
aux.resize(array.size());
//aux = array;
merge_sort(array, aux, 0, size - 1);

cout<<"The sorted array is:"<<endl;
Print(array);

//cout<<"Comparing count is: "<<COMPARE_COUNT<<endl;

return 0;
}

输出结果：