N！Again
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 3803 Accepted Submission(s): 2036
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
Sample Output
这题最容易想到的是2009以后全是0。。。至少我第一次A的代码就是这个思路。2009以前的打表~~
其次，2009=41*7*7。所以40以后全都是0了。至于40以前的也是打表呗~
附上我的代码：
#include <stdio.h>
#define MAX 2009
int ans[MAX] ;
int main()
{
int n ;
ans[0] = 1 ;
for(int i = 1 ; i < MAX ; ++i )
{
ans[i] = (ans[i-1]*i)%MAX ;
}
while(~scanf("%d",&n))
{
if(n>=2009)
{
puts("0") ;
}
else
{
printf("%d\n",ans[n]) ;
}
}
return 0;
}
与君共勉hdu 2674 N！Again 数论水题啊~~~
原文：http://blog.csdn.net/lionel_d/article/details/44241493
