面试 快排

int quicksort(vector<int> &v, int left, int right){        if(left < right){                int key = v[left];                int low = left;                int high = right;                while(low < high){                        while(low < high && v[high] > key){                                high--;                        }                        v[low] = v[high];                        while(low < high && v[low] < key){                                low++;                        }                        v[high] = v[low];                }                v[low] = key;                quicksort(v,left,low-1);                quicksort(v,low+1,right);        }}