快速排序

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
void quick_sort(vector<int> & num,int left,int right)
{
    if(left>=right)//如果递归到了尽头就直接返回 
        return;
    int low=left;
    int high=right;
    int base=num[left];//选定最左边的为基准
    while(low<high)
    {
        while(num[high]>=base&&low<high)//先从右向左找小于base的
        {
            high--;
        }
        num[low]=num[high];
        while(num[low]<=base&&low<high)//从左向右找第一个大于base的
        {
            low++;
        }
        num[high]=num[low];
    }
    num[low]=base;//将基准放到high==low这个位置
    quick_sort(num,left,low-1);//接下来递归下一层
    quick_sort(num,high+1,right);
}
int main()
{
    vector<int> num;
    for(int i=1;i<=5;i++)
    {
        int t;
        cin>>t;
        num.push_back(t);
    }
    quick_sort(num,0,4);
    for(auto &i:num)
        cout<<i<<" ";
    return 0;
}

快排就是一个分治的思想，将大于基准的放一边，小于的放一边，然后继续下一层