题解 | #提取不重复的整数#

import java.util.Scanner;

import java.util.LinkedHashSet;

// 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);
        String str = scanner.nextLine();
        //借用StringBuffer中的数组反转函数
        StringBuilder stringBuilder = new StringBuilder(str);
        StringBuilder strReverse = stringBuilder.reverse();
        //LinkedHashSet会记住存入元素的顺序，并有去重复功能
        LinkedHashSet<Character> set = new LinkedHashSet<>();
        for (int i = 0; i < strReverse.length(); i++) {
            set.add(strReverse.charAt(i));
        }
        Character[] characters = set.toArray(new Character[] {});
        for (int i = 0; i < characters.length; i++) {
            System.out.print(characters[i]);
        }
        scanner.close();

    }
}