题解 | #提取不重复的整数#

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner fzhinput = new Scanner(System.in);
        int x;
        int n = fzhinput.nextInt();
        StringBuilder stack = new StringBuilder();
        Set <Integer> seen = new HashSet<>();
        while(n>10){
            x = n%10;
            if(!seen.contains(x)){
                stack.append(x);
                seen.add(x);
            }
            n/=10;
        }
        if(!seen.contains(n)){
                stack.append(n);
                seen.add(n);
        }
        System.out.println(stack);
    }
}