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 in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNextInt()) { // 注意 while 处理多个 case
            int num = in.nextInt();

            int newNum = notContainDuplicateNumber(num);
            System.out.println(newNum);
        }
    }

    private static int notContainDuplicateNumber(int num) {
        HashSet<Integer> set = new HashSet<>();
        Deque<Integer> stack = new ArrayDeque<Integer>();

        while (num > 0) {
            int bitNum = num % 10;
            if (!set.contains(bitNum)) {
                set.add(bitNum);
                stack.addLast(bitNum);
            }
            num = num / 10;
        }

        int result = 0;
        int count = 0;
        while (!stack.isEmpty()) {
            int bitNum = stack.removeLast();
            result += bitNum * Math.pow(10, count);
            count += 1;
        }
        return result;
    }
}