HDUOJ 2674 N！Again

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N！Again

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 5915    Accepted Submission(s): 3149

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

 

Author

WhereIsHeroFrom

 

Source

HDU女生专场公开赛——谁说女子不如男

AC：

#include<stdio.h>
int main()
{
	int n,mod,i,sum;
    int a[50];
    a[0]=1;
    for(i=1;i<=50;i++)
    {
    	a[i]=(a[i-1]*i)%2009;
	}
	while(scanf("%d",&n)!=EOF)
	{
		if(n>40)
		  printf("0\n");
		else
		  printf("%d\n",a[n]);
	}
    return 0;	
}

因为2009=41*7*7；

所以，41之后的都为0.