快速排序

#include <cstdio>
#define ARRLEN(x) (sizeof(x)/sizeof(int))
int partition(int a[], int low, int high)
{
    int pivotkey=a[low];
    while (low<high)
    {
        while (low<high && a[high]>=pivotkey)
            --high;
        if (low<high)
            a[low++]=a[high];
        while (low<high && a[low]<=pivotkey)
            ++low;
        if (low<high)
            a[high--]=a[low];
    }
    a[low]=pivotkey;
    return low;
}
void quicksort(int a[], int low, int high)
{
    int pivotpos;
    if (low<high)
    {
        pivotpos=partition(a,low,high);
        quicksort(a,low,pivotpos-1);
        quicksort(a,pivotpos+1,high);
    }
}
int main()
{
    int a[]={2,7,9,3,1,4,8,0,6,2};
    int i;
    for (i=0; i<ARRLEN(a); printf("%2d",a[i]),++i);
    printf("/n");
    quicksort(a,0,ARRLEN(a)-1);
    for (i=0; i<ARRLEN(a); printf("%2d",a[i]),++i);
    printf("/n");
    return 0;
}