题解 | #HJ009 提取不重复的整数#

import java.util.*;

/**
 * HJ9 提取不重复的整数 2752771  1725
 */
public class HJ009 {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        List<Character> list = new ArrayList<>();
        StringBuffer str = new StringBuffer(sc.nextLine());
        str = str.reverse();
        for (int i = 0; i < str.length(); i++) {
            char c = str.charAt(i);
            if (!list.contains(c)) {
                list.add(c);
            }
        }
        StringBuffer str2 = new StringBuffer();
        for (Character c : list) {
            str2.append(c);
        }
        System.out.println(str2);
        sc.close();
    }

}