public class Main{
    public static void main(String args[]){
    	Scanner in=new Scanner(System.in);
    	int n=in.nextInt();
    	Integer[] a=new Integer[n];
    	for(int i=0;i<n;i++) {
    		a[i]=in.nextInt();
    	}
    	Arrays.sort(a,(x,y)->{return (y%1000)-(x%1000);});
    	for(int i=0;i<n;i++) {
    		System.out.print(a[i]+" ");
    		
    	}
    }
}

使用桶排序效率更高 Python

a = [-1] * 1000
n = int(input())
nums = list(map( int,input().split(" ")))
for i in nums:
    a[-(i  % 1000 + 1)] = i
[print(i , end = " ") for i in a if i != -1]

这个办法是构建一个Num类,来进行排序

import java.util.Arrays;
import java.util.Scanner;


public class Main {
    public static void main(String[] args) {
        //   HashMap<Integer, String> map = new HashMap<>();
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        Num[] a = new Num[n];
        for (int i = 0; i < n; i++) {
            a[i] = new Num();
            String num = sc.next();
//如果该对象的num长度大于3, 就令aa值等于num的后三位
            if(num.length() > 3){
                a[i].val = num;
                a[i].aa = Integer.parseInt(num.substring(num.length() - 3));
            }else {//否则aa值等于num值
                a[i].val = num;
                a[i].aa = Integer.parseInt(num);
            }
        }

        //自定义排序效果与冒泡排序相同
        Arrays.sort(a, (o1, o2) -> (o1.aa - o2.aa));
        //冒泡排序, 给aa值大的对象排后面
//        for (int i = 0; i < a.length - 1; i++) {
//            for (int j = 0; j < a.length - i - 1; j++) {
//                if(a[j].aa < a[j + 1].aa){
//                    Num temp = a[j];
//                    a[j] = a[j + 1];
//                    a[j + 1] = temp;
//                }
//            }
//        }
        for (int i = 0; i < a.length; i++) {
            System.out.print(a[i].val + " ");
        }
    }
}
class Num{
    String val; //该数字的值
    int aa; //后三位的值
}