双向快速排序

#include <iostream>
using namespace std;

void swap(int* p,int* q)
{
    int temp = *p;
    *p = *q;
    *q = temp;
}

//快速排序
int partition(int *ptr,int first, int last)
{
    int temp = ptr[first];
    int i = first + 1, j = last;
    while(i < j)
    {
        while(ptr[i] < temp && i <= last)
            ++i;
        while(ptr[j] > temp)
            --j;
        if(i < j)
        {
            swap(&ptr[i],&ptr[j]);
            ++i;
            --j;
        }    

    }

    swap(&ptr[first],&ptr[j]);
    return j;
} 

void quickSort(int *ptr,int first,int last)
{
    if(first < last)
    {
        int q = partition(ptr,first,last);

        quickSort(ptr,first,q-1);
        quickSort(ptr,q+1,last);
    }
}
int main()

{
    int a[] = {2,23,45,1,8,2,0};
     for(int i =0; i <= 6; ++i)
    {
        std::cout << a[i] << " ";
    }
    cout << endl;
    //mergeSort(a,0,6);
    quickSort(a,0,6);
    for(int i =0; i <= 6; ++i)
    {
        std::cout << a[i] << " ";
    }
    std::cout << std::endl;
    return 0;
}