题解 | #数字颠倒#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        Integer a = in.nextInt();
        StringBuilder stringBuilder = new StringBuilder(a.toString()); //必须转为字符串，否者输出空
        stringBuilder.reverse();
        System.out.println(stringBuilder);
    }
}