快排查找第K小的数

#include "iostream.h"
using namespace std;
int findMedian(int *A,int left,int right){
	int center = (left+right)/2;
	if(A[left]>A[center]){
		swap(A[left],A[center]);
	}
	if(A[left]>A[right]){
		swap(A[left],A[right]);
	}
	if(A[center]>A[right]){
		swap(A[center],A[right]);
	}
	//A[right]已经大于A[center] 
	swap(A[center],A[right-1]);
	return A[right-1];
	
}
void insertSort(int *A, int left,int right){
	
	for(int i=left+1;i<=right;i++){
		int p = A[i];
		int j;
		for( j=i;j>=left&&A[j-1]>p;j--){
			A[j]=A[j-1];
		}
		A[j]=p;
	}
}
#define CUTOFF 5
int qselect(int *A, int k, int left,int right){
	if(left+CUTOFF
  






   pivot){}
			if(i
   
    =pivot&&A[j]<=pivot,交换二者位置 swap(A[i],A[j]); }else break; } swap(A[i],A[right-1]); int t = i-left+1; if(k==t) return A[i]; else if(k
    
     >N; for(int i=0;i
     
      >A[i]; } int k; cin>>k; if(k<=N-0) cout<