快速排序算法

//快速排序
#include<iostream>
using namespace std;
int partition(int *arr,int low,int high)
{
    int pivotkey=arr[low];
    while(low<high)
    {
        while(low<high&&arr[high]>=pivotkey)
            --high;
        arr[low]=arr[high];
        while(low<high&&arr[low]<=pivotkey)
            ++low;
        arr[high]=arr[low];               
    }
    arr[low]=pivotkey;
    return low;    
} 
void sort(int *arr,int low,int high)//通过递归函数进行快速排序 
{
     if(low<high)
     {
         int pivot=partition(arr,low,high);
         sort(arr,low,pivot-1);
         sort(arr,pivot+1,high);            
     }    
}
int sortNum(int *arr,int s,int t,int seq)//通过快速排序  搜索出第seq个数 
{
    int low=s;