HDU-2018 母牛的故事 C/C++ 递推

HDU-2018 母牛的故事

Problem Description

有一头母牛，它每年年初生一头小母牛。每头小母牛从第四个年头开始，每年年初也生一头小母牛。请编程实现在第n年的时候，共有多少头母牛？

Input

输入数据由多个测试实例组成，每个测试实例占一行，包括一个整数n(0

Output

对于每个测试实例，输出在第n年的时候母牛的数量。 每个输出占一行。

Sample Input

2
4
5
0

Sample Output

2
4
6

My first passage on CSDN.The reason why I use English is that my tpewritting is so lame.
But it might not be a bad thing for me to do this in English.

I attempts for times but all I got are WA! At first I use recursion（di gui） to solve the peoblem,but I gave up.
Finally I searched it on the internet and knew all it need is just the recurision(di tui??)

(p.s Why digui and ditui use the same word in Eng??)

This is my code.

#include
int main()
{
	int cow[56],n;
	cow[0]=0;cow[1]=1;cow[2]=2;cow[3]=3;//先确定前几年的个数,可以在纸上自己画一下 
	for(int i=4;i<=55;i++){//递推 
			cow[i]=cow[i-1]+cow[i-3];
		}
	while(scanf("%d",&n)==1&&n){//按题目要求输入输出 
		printf("%d\n",cow[n]);
	}
	return 0;
}