题解 | #提取不重复的整数#

import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.IOException;
import java.util.Set;
import java.util.HashSet;

public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String str = reader.readLine();
        int i = str.length() - 1;
        Set<Character> set = new HashSet<>();
        int res = 0;
        while(i >= 0){
            char c = str.charAt(i);
            if(!set.contains(c)){
                res = res * 10 + c - '0';
                set.add(c);
            }
            i--;
        }
        System.out.println(res);
    }
}