题解 | #提取不重复的整数#

import java.util.*;

// 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);
        StringBuilder stringBuilder = new StringBuilder();
        String s = scanner.nextLine();
        ArrayList<String> strings = new ArrayList<>();
        for (int i = s.length() - 1; i >= 0; i--) {
            String s1 = String.valueOf(s.charAt(i));
            if (! strings.contains(s1)) {
                strings.add(s1);
            }
        }
        for (String string : strings) {
            stringBuilder = stringBuilder.append(string);
        }
        System.out.println(stringBuilder.toString());
    }
}