题解 | #提取不重复的整数#

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

public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        while (in.hasNextLine()) {
            String numStr = in.nextLine();
            Set<Character> visited = new HashSet<>();
            for (int i = numStr.length() - 1; i >= 0; i--) {
                char c = numStr.charAt(i);
                if (!visited.contains(c)) {
                    visited.add(c);
                    System.out.print(c);
                }
            }
            System.out.println();
        }
    }
}