题解 | #提取不重复的整数#

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int number = sc.nextInt();
        String num = String.valueOf(number);
        Set<Character> set = new HashSet<>();
        StringBuilder sb = new StringBuilder();
        for (int i = num.length() - 1; i >= 0; i--) {
            char c = num.charAt(i);
            if (set.add(c)) {
                sb.append(c);
            }
        }
        System.out.println(Integer.parseInt(sb.toString()));
    }
}