快速排序

c++版：

#include <iostream>
//快速排序
void quick_sort(int s[], int l, int r)
{
    if (l < r)
    {
        std::swap(s[l], s[(l + r) / 2]); //将中间的这个数和第一个数交换 参见注1
        int i = l, j = r, x = s[l];
        while (i < j)
        {
            while(i < j && s[j] >= x) // 从右向左找第一个小于x的数
                j--;  
            if(i < j) 
                s[i++] = s[j];
            
            while(i < j && s[i] < x) // 从左向右找第一个大于等于x的数
                i++;  
            if(i < j) 
                s[j--] = s[i];
        }
        s[i] = x;
        quick_sort(s, l, i - 1); // 递归调用 
        quick_sort(s, i + 1, r);
    }
}

int main(){
    int A[5] ={2, 4, 1, 3, 5};
    quick_sort(A, 0, 4);
    for (int i = 0; i<5; ++i) {
        if(i) printf(" ");
        printf("%d", A[i]);
    }
    return 0;
}

c++精简版：

#include<cstdio>
#include<cstdlib>
#include<algorithm>
#include <cmath>
using namespace std;
 
int Partition(int A[], int left, int right){
    int p = round(1.0*rand()/RAND_MAX*(right - left) + left);
    swap(A[p], A[left]);
 
    int temp = A[left];
    while(left < right> temp) right--;
        A[left] = A[right];
        while(left<right && A[left] &lt;= temp) left++;
        A[right] = A[left];
    }
    A[left] = temp;
    return left;
}
 
void quickSort(int A[], int left , int right){
    if (left<right){
        int pos = Partition(A, left, right);
        quickSort(A, left, pos -1);
        quickSort(A, pos + 1, right);
    }
}
 
int main(){
    int A[5] ={2, 4, 1, 3, 5};
    quickSort(A, 0, 4);
    for (int i = 0; i < 5; ++i) {
        if(i) printf(" ");
        printf("%d", A[i]);
    }
    return 0;
}

python 版：

    def quick_sort(li):
        # 被分解的Nums小于1则解决了
        if len(li) <= 1:
            return li
        
        # 分解    
        temp = li[0]
        left = [i for i in li[1:] if i < temp xss=removed>= temp]
        
        # 递归求解即分治
        left = quick_sort(left)
        right = quick_sort(right)
        # 合并
        return left + [temp] + right
     
    quick_sort(nums2)

转载自：https://blog.csdn.net/morewindows/article/details/6684558
https://www.runoob.com/w3cnote/quick-sort.html