HDU 2674 N!Again
阿新 • • 發佈:2018-12-14
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
程式碼及註釋如下:
/* 2009及之後的mod2009都等於0; 前面的測了一下發現41mod2009就等於0了... 綜上40之後的mod2009=0. 40之前的需要算一波 */ #include <cstdio> #include <cstring> #include <algorithm> #include <iostream> using namespace std; int a[50]; int n; void Init() { a[0]=1; a[1]=1; for (int i=2;i<=40;i++) { a[i]=a[i-1]*i%2009; } } int main() { Init(); while (scanf("%d",&n)!=EOF) { if(n<=40) printf("%d\n",a[n]); else printf("0\n"); } return 0; }