【水题+数学推导】杭电 hdu 2018 母牛的故事

/* THE PROGRAM IS MADE BY PYY */
/*----------------------------------------------------------------------------//
    Copyright (c) 2012 panyanyany All rights reserved.

    URL   : http://acm.hdu.edu.cn/showproblem.php?pid=2018
    Name  : 2018 母牛的故事

    Date  : Thursday, February 16, 2012
    Time Stage : half an hour

    Result:
5361461	2012-02-16 16:47:38	Accepted	2018
0MS	216K	982 B
C++	pyy


Test Data :

Review :
//----------------------------------------------------------------------------*/

#include 

#define MAXN	(56)

#define DB	/##/

int can[MAXN] = {0, 1, 1, 1, 1}, cow[MAXN] ;

int main ()
{
	int i, j, n ;
	// 计算第i年有多少头可生育的母牛
	for (i = 5 ; i <= 55 ; ++i)
		can[i] = can[i-1] + can[i-3] ;

	// 根据今年可生育的母牛数，和上一年的总牛数，可以算出今年的总牛数。
	cow[0] = 0 ;
	for (i = 1 ; i <= 55 ; ++i)
		cow[i] = cow[i-1] + can[i] ;
	while (scanf("%d", &n), n)
	{
		printf ("%d\n", cow[n]) ;
	}
	return 0 ;
}