题解 | #表示数字#

using System;

namespace HJ96{
    class Solution{
        public static void Main(){
            var input = Console.ReadLine().Trim().ToCharArray();
            
            for(int i = 0; i < input.Length; i++){
                
                if(i != 0 && Char.IsNumber(input[i]) &&  !Char.IsNumber(input[i-1])){//当前数字，前面不是数字
                    Console.Write("*");
                }else if(i==0 && Char.IsNumber(input[i])){//当前数字且开头
                     Console.Write("*");
                }
                
                Console.Write(input[i]);
                
                if( i!=input.Length-1 && Char.IsNumber(input[i]) &&  !Char.IsNumber(input[i+1])){//当前数字，后面不是数字
                    Console.Write("*");
                }else if(i == input.Length-1 && Char.IsNumber(input[i])){//当前数字且末尾
                     Console.Write("*");
                }               
            }            
        }
    }
}