hduoj2802F（N）

F(N)

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 3202    Accepted Submission(s): 1106

Problem Description

Giving the N, can you tell me the answer of F(N)?

 

Input

Each test case contains a single integer N(1<=N<=10^9). The input is terminated by a set starting with N = 0. This set should not be processed.

 

Output

For each test case, output on a line the value of the F(N)%2009.

 

Sample Input

   
   
   
   

    
    
    
    1
2
3
0
   
   
   
   

 

Sample Output

   
   
   
   

    
    
    
    1
7
20
   
   
   
   

 

知识点：鸽巢原理、递推

#include<iostream>
using namespace std;

int main()
{  int a[5000];
   a[1]=1;
   a[2]=7;
   int i,n;
   for(i=3;i<=4018;i++)
    {a[i]=a[i-2]+3*i*(i-1)+1;
      if(a[i]>2009) a[i]=a[i]%2009;}
   while(cin>>n,n)
   {
       cout<<a[n%4018]<<endl;
   }
    return 0;
}