2015 HUAS Provincial Select Contest #3 C

题目：

The Coco-Cola Store

Once upon a time, there is a special coco-cola store. If you return three empty bottles to the shop, you’ll get a full bottle of coco-cola to drink. If you have n empty bottles right in your hand, how many full bottles of coco-cola can you drink?

Input

There will be at most 10 test cases, each containing a single line with an integer n (1 ≤ n ≤ 100). The input terminates with n = 0, which should not be processed.

Output

For each test case, print the number of full bottles of coco-cola that you can drink.

Spoiler

Let me tell you how to drink 5 full bottles with 10 empty bottles: get 3 full bottles with 9 empty bottles, drink them to get 3 empty bottles, and again get a full bottle from them. Now you have 2 empty bottles. Borrow another empty bottle from the shop, then get another full bottle. Drink it, and finally return this empty bottle to the shop!

题目大意：有N个空杯子，3个杯子能换一杯满的饮料，求最多能喝多少杯？

解题思路：sum+=(n/3); n=n%3+n/3用这两个式子，第一个存储商，一个存储余数加商做下轮的除数，当n=2是可以先喝一杯再把3个杯子叫上去。n<=1是可以直接退出循环。

代码: 

#include<iostream>
#include<cstdio>
using namespace std;
int main()
{
    int n,sum;
    while(cin>>n)
    {
        if(n>=1&&n<=100)
        {
            sum=0;
            while(1)
            {
                if(n==2)
                {
                    sum+=1;
                    break;
                }
                else 
                    sum+=(n/3);
                n=n%3+n/3;
                if(n<=1)
                    break;
            }
            printf("%d
",sum);
        }
        else break;
    }
    return 0;
}
 

 

				else 
					sum+=(n/3);
				n=n%3+n/3;
				if(n<=1)
					break;
			}
			printf("%d
",sum);
		}
		else break;
	}
	return 0;
}