C语言实现快排

#include <stdio.h>

void swap(int *pa, int *pb)
{
    int t = *pa;
    *pa = *pb;
    *pb = t;
}

int partion(int *array, int begin, int end)
{
    if (array == NULL || begin < 0 || end < 0)
        return -1;
    int pivot = array[end];
    int small = begin -1;
    for(int i = begin; i < end; i++ ){
        if(array[i] <= pivot) {
            ++small;
            if(small != i){
                swap(&array[small], &array[i]);
            }
        }
    }
    swap(&array[++small], &array[end]);
    return small;
}

void qsort(int array[], int begin, int end)
{
    if (end == begin)
        return;
    int index = partion(array, begin, end);
    if (index == -1)
        return;
    if (index > begin)
        qsort(array, begin, index - 1);
    if (end > index)
        qsort(array, index + 1, end);
}

void display(int a[], int n)
{
    for(int i = 0; i < n; i ++)
        printf("%d ", a[i]);
    printf("\n");
}

int main()
{
    int a[] = {5, 4, 3, 2,6};
    int n = sizeof(a)/sizeof(a[0]);
    display(a, n);
    qsort(a, 0, n -1);
    display(a, n);
}