题解 | #汽水瓶#

using System;
// using System.Collections.Generic;

namespace HJ22{
    class Solution{

        //方法一：找规律 3-2 4-2 5-2 6-3 7-3 8-4 9-4 ....

        public static void Main(){
            int n = 0;
            while((n = int.Parse(Console.ReadLine())) !=0){
                if(n != 0){
                    Console.WriteLine(n/2);
                }            
            }            
        }


        //方法二：递归 f(n)=n/3 + f(n%3 + n/3)
        
        public static void Main(){
            int n = 0;
            while((n = int.Parse(Console.ReadLine())) !=0){
                if(n != 0){
                    n = calNum(n);
                    Console.WriteLine(n);
                }    
            }    
        }
//         static Dictionary<int, int> map = new Dictionary<int, int>();
        public static int calNum(int num){
            int res;
            if(num == 1){
                return 0;            
            }else if(num == 2){
                return 1;
            }
            
//             if(map.ContainsKey(num)){
//                 map.TryGetValue(num, out res);
//                 return res;
//             }
            res = num/3 + calNum(num%3+num/3);
//             map.Add(num, res);         
            return res;                                 
        }
    }
}