#include 
     
      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); }