题解 | #表示数字#

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);
        String str_old = in.nextLine();
        char[] char_old = str_old.toCharArray();
        StringBuilder str_new = new StringBuilder();
        for (int i = 0; i < char_old.length; i++) {
            if (Character.isDigit(char_old[i]) && (i == 0 ||
                                                   !Character.isDigit(char_old[i - 1]))) {
                str_new.append("*");
                str_new.append(char_old[i]);

            } else if (i > 0 && Character.isDigit(char_old[i - 1]) &&
                       !Character.isDigit(char_old[i])) {
                str_new.append("*");
                str_new.append(char_old[i]);

            } else {
                str_new.append(char_old[i]);

            }
            if (Character.isDigit(char_old[i]) && i == char_old.length - 1) {
                str_new.append("*");

            }

        }
        System.out.println(str_new);

    }
}