快速排序算法

#include <stdio.h>                                                                                                                                                                          
#include <stdlib.h>

void swap(int *a, int *b)
{
    int tmp;
    tmp = *a;
    *a = *b;
    *b = tmp;
}


int partition(int array[], int start, int end)
{
    int index;
    int flag;
    int x = array[end];

    flag = start - 1;
    for(index = start; index < end; index++) {
        if (array[index] < x) {
            flag++;
            if (flag != index) {
                swap(&array[flag], &array[index]);
            }
        }
    }
    flag++;
    swap(&array[flag], &array[end]);
    return flag;
}


int partition1(int array[], int begin, int end)
{
    int i;
    int j;
    int p;

    p = array[begin];

    i = begin + 1;
    j = end;
    while (i < j) {
        while ((i < j) && (array[j] > p))
            j--;
        while ((i < j) && (array[i] < p))
            i++;
        if (i < j)
            swap(&array[i], &array[j]);
    }
    if (array[i] < p)
       swap(&array[begin], &array[i]);
    return i;
}


void quick_sort(int array[], int start, int end)
{
    int index;

    if (start >= end)
        return;

    index = partition1(array, start, end);

    quick_sort(array, start, index-1);
    quick_sort(array, index+1, end);
}

int main(int argc, char *argv[])
{
    int i;
    int a[] = {100, 45, 3, 5,78,23,9,2,0,57};

    int len;
    len = sizeof(a)/sizeof(a[0]);
    quick_sort(a, 0, len - 1);

    for (i = 0; i < len; i++) 
        printf("%d ", a[i]);
    printf("\n");
    return 0;
}