Hduoj2802【水题】

F(N)

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 4021    Accepted Submission(s): 1409

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
   
   
   
   

 

Source

HDU 2009-4 Programming Contest 

#include<stdio.h>
int main()
{
	__int64 i, j, k, n, f[4019];
	f[1] = 1;
	f[2] = 7;
	for(i = 3; i <= 4018; ++i)
	{
		f[i] = f[i-2] + 3*i*(i-1) + 1;
		f[i] %= 2009;
	}
	while(scanf("%I64d", &n) != EOF && n)
	{
		n %= 4018;
		printf("%I64d\n", f[n]);
	}
	return 0;
}

题意：给一个公式，给一个数，让你求值。

思路：先是自己打表找循环节，再根据循环节来打表，另外要注意范围。