题解 | #提取不重复的整数#

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 in = new Scanner(System.in);
        int num = in.nextInt();
        String str = String.valueOf(num);
        int size = str.length();
        LinkedHashMap<Character, Character> map = new LinkedHashMap<>(size);
        char[] arr = str.toCharArray();
        for (int i = size - 1; i >= 0; i--) {
            map.put(arr[i], arr[i]);
        }
        for (Character c : map.keySet()) {
            System.out.print(c);
        }
    }
}