快速排序

import java.io.BufferedInputStream;
import java.util.Scanner;

public class Main{
    public static void main(String[] args) {
        Scanner scan = new Scanner(new BufferedInputStream(System.in));
        int n = scan.nextInt();
        int[] arr = new int[n];
        for(int i =  0; i < n; i++) {
            arr[i] = scan.nextInt();
        }
        method(arr,0,n - 1);
        for(int i = 0; i < n; i++) {
            System.out.print(arr[i] + " ");
        }
    }
    public static void method(int[] arr,int l,int r) {
        if(l >= r) return;
        int i = l - 1, j = r + 1, x = arr[(l + r) / 2]; //初始从左边界的前一个与右边界的后一个开始，因为不管现状如何，都嫌do++操作
        while(i < j) {
            do {
                i++;
            }while(arr[i] < x);
            do {
                j--;
            }while(arr[j] > x);
            if(i < j) {
                int temp = arr[i];
                arr[i] = arr[j];
                arr[j] = temp;
            }
        }
        method(arr, l, j); //此时j <= i
        method(arr, j + 1, r);
    }
}