题解 | #数字颠倒#

import java.util.*;

// 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 scanner = new Scanner(System.in);
        int i = scanner.nextInt();

        String s = String.valueOf(i);
        String[] split = s.split("");//拆分输入整数字符串

        HashMap<Integer, String> hash = new HashMap<>();
        for (int j = split.length-1; j >=0; j--) {
            String s1 = split[j];//将数组依据下标从后向前放入map
            hash.put(j,s1);
        }
        StringBuilder sb = new StringBuilder();
        for (int j = split.length-1; j >=0; j--) {
            String s1 = hash.get(j);//从map中从后向前取出value后进行stringbuider拼接字符串
            sb=sb.append(s1);
        }
        System.out.print(sb);
    }
}