快速排序

普通快速排序代码如下：

#include<iostream>
#include<algorithm>
#include<vector>
#include<set>
using namespace std;
int getindex(vector<int>&arr,int m,int left,int right){
    bool flag=true;
    while(left<right){
        if(flag){
            if(arr[right]>=m){
            right--;
        }
        else{
            arr[left++]=arr[right];
            flag = false;
        }

        }

        else{
        if(arr[left]<=m){
            left++;
        }
        else{
            arr[right--]=arr[left];
            flag=true;
        }

        }
    }
    arr[left]=m;
    return left;
}
void quicksort(vector<int>&arr,int left,int right){
    int mid= getindex(arr,arr[left],left,right);
    if(left<mid-1)
       quicksort(arr,left,mid-1);
    if(right>mid+1)
       quicksort(arr,mid+1,right);
}
int main(){
    vector<int>arr={1,5,3,9,4,56,234,71,3,52,7};
    quicksort(arr,0,arr.size()-1);
    for(int t:arr){
        cout<<t<<" ";
    }
}