题解 | #提取不重复的整数#

import java.util.*; 
import java.io.*;

// 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) {
       BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        try {
            LinkedHashSet<Integer> set = new LinkedHashSet<>();
            char[] chars = br.readLine().toCharArray();
            for (int i = chars.length - 1; i >= 0; i--) {
                set.add(Integer.valueOf(chars[i]+""));
            }
            for (Integer integer : set) {
                System.out.print(integer);
            }

        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}