题解 | #提取不重复的整数#

import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;

// 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);
        String num = in.next();
        StringBuilder sb1 = new StringBuilder(num);
        StringBuilder sb2 = sb1.reverse();
        StringBuilder sb3 = new StringBuilder();
        Map<Integer,String> m1= new TreeMap<>();
        int t = 0;
        for (int i = 0; i < sb2.length(); i++) {
            if(!m1.containsValue(String.valueOf(sb2.charAt(i)))){
                m1.put(t,String.valueOf(sb2.charAt(i)));
                t++;
            }
        }
        for (int i = 0; i <t; i++) {
            System.out.print(m1.get(i));
        }

    }
}