quick sort实现

/*
　　
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>

int partition(int *a, int start, int end, int key)
{
    int i = start, j = end;
    
    while (1)
    {
        while (a[j] >= key)
        {
            j--;
            if (j == start) {
                return start;
            }
        }
        while (a[i] <= key && i <= end) {
            i++;


        }
        if (i < j)
        {
            int tmp;
            tmp = a[i];
            a[i] = a[j];
            a[j] = tmp;
        }
        else
            return j;
    }
}

void quick_sort(int *a, int start, int end)
{
    if (start < end)
    {
        int q = partition(a, start, end, a[start]);
        int tmp;
        tmp = a[start];
        a[start] = a[q];
        a[q] = tmp;
        quick_sort(a, start, q - 1);
        quick_sort(a, q + 1, end);
    }
}

int main()
{
    int a[] = {9, 8, 10, 2, 1, 19, 10, 20};
    int aa[] = {19,19,19, 19};
    quick_sort(a, 0, sizeof(a) / sizeof(int) - 1);
    for (int i = 0; i < sizeof(a) / sizeof(int); i++) {
        printf("%d ", a[i]);
    }
    printf("\n");
}