Quick Sort

#include <iostream>
using namespace std;

void QuickSortCore(int a[], int start, int end)
{
    if (start > end)
        return;
    int key = a[start];
    int blank = start;
    int left = start + 1;
    int right = end;

    while(left <= right){//维护left right blank key
        if (blank < left){
            if (key <= a[right]){
                right--;
                continue;
            }
            else{
                a[blank] = a[right];
                blank = right--;
                continue;
            }
        }
        else if (blank > right){
            if (key >= a[left]){
                left++;
                continue;
            }
            else{
                a[blank] = a[left];
                blank = left++;
                continue;
            }
        }
    }
    a[blank] = key;

    QuickSortCore(a, start, blank - 1);
    QuickSortCore(a, blank + 1, end);
}

void QuickSort(int a[], int len){
    if (!a || len < 0)
        return;

    QuickSortCore(a, 0, len-1);
}


int main()
{
    int a[] = {3,6,5,81,94,53,0,12,4,2,4,2,1};
    QuickSort(a, 13);
    return 0;
}

EOF