题解 | #表示数字#

import java.util.Scanner;

// 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);
        String source = in.nextLine();
        boolean open = true;
        StringBuilder result = new StringBuilder();
        for (int i = 0; i < source.length(); i++) {
            char c = source.charAt(i);
            boolean b = c >= '0' && c <= '9';
            if (b && open) {
                result.append("*");
                open = false;
            } else if (!b && !open) {
                result.append("*");
                open = true;
            }

            result.append(c);

            if (i == source.length() - 1 && b) {
                result.append("*");
            }
        }
        System.out.println(result);
    }
}