题解 | #提取不重复的整数#

import java.util.Scanner;
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 in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            long a = in.nextInt();
            long b = removeDupFromLeftToRight(a);
            System.out.println(b);
        }
    }

    public static long removeDupFromLeftToRight(long num) {
        String str = String.valueOf(num);

        //从右到左，set去重
        Set<Character> set1 = new LinkedHashSet<>();
        for(int i=str.length()-1; i>=0; i--) {
            set1.add(str.charAt(i));
        }

        //变回字符串
        String str2 = "";
        for(Character ch: set1) {
            str2 = str2 + ch;
        }
        //System.out.println("str2: " + str2);

        //变回int
        long result = Long.parseLong(str2);

        return result;
    }

}