题解 | #提取不重复的整数#

import java.util.Scanner;
import java.util.HashSet;

// 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 num = scanner.nextInt();

        HashSet<Character> set = new HashSet<>();
        String string = num + "";
        char[] array = string.toCharArray();
        int res = 0;
        for (int i = array.length - 1; i >= 0; i--) {
            if (!set.contains(array[i])) {
                set.add(array[i]);
                res = res * 10 + (array[i] - '0');
            }
        }
        System.out.println(res);
    }
}