HDU 2018

母牛的故事  也可以用递归公式写 f（n） = f（n-1）+f（n-3）；

HDU 2018

 /* THE PROGRAM IS MADE BY SH */
/*---------------------------------------------------------------------------
 *       http://acm.hdu.edu.cn/showproblem.php?pid=2018
 *       母牛的故事 
 *       Date  : 2015/5/1 
----------------------------------------------------------------------------*/
#include 
#include 
#include 
#include 
#include 
#include 
#include 

using namespace std;

int main()
{
  int n;
  int a[100] = {0};
  while(scanf("%d",&n) != EOF && n > 0 && n < 55) {
      if( n == 0) break;;
      if(n <= 4){
          printf("%d\n",n);
      }
      else if(n > 4){
          for(int i = 1; i <= n; ++i){
              if( i <= 4){
                  a[i] = i;
              }
              else if(i >4){
                  a[i] = a[i-1]+a[i-3];     
              }              
          }
          printf("%d\n",a[n]);
      }
   }
  system("Pause");
  return 0;
}