杭电-2674N！Again（大数阶乘）

N！Again

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 4267    Accepted Submission(s): 2279

Problem Description

WhereIsHeroFrom:             Zty, what are you doing ?
Zty:                                     I want to calculate N!......
WhereIsHeroFrom:             So easy! How big N is ?
Zty:                                    1 <=N <=1000000000000000000000000000000000000000000000…
WhereIsHeroFrom:             Oh! You must be crazy! Are you Fa Shao?
Zty:                                     No. I haven's finished my saying. I just said I want to calculate N! mod 2009


Hint : 0! = 1, N! = N*(N-1)!

 

Input

Each line will contain one integer N(0 <= N<=10^9). Process to end of file.

 

Output

For each case, output N! mod 2009

 

Sample Input

4 
5

 

Sample Output

24
120

 

大数阶乘，但是规律是41及其以后取余2009都为0，一定要优化这一句，否则超时

#include<cstdio>
#include<cstring>
#include<algorithm>
using namespace std;
long long solve(long long  n)
{
	long long t=1;
	for(long long i=n;i>=2;i--)
		t=i*t%2009;
	return t;
}
int main()
{
	long long a,n,i;
	while(scanf("%lld",&n)!=EOF)
	{
		if(n>=41)
		printf("0\n");
		else
		{
			a=solve(n);
			printf("%lld\n",a);
		}
	}
	return 0;
}