HDU2674 N！Again 【數學】

標籤：hdu2674

N！AgainTime Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 3440    Accepted Submission(s): 1865

Problem DescriptionWhereIsHeroFrom:             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)!
 
InputEach line will contain one integer N(0 <= N<=10^9). Process to end of file.
 
OutputFor each case, output N! mod 2009
 
Sample Input

4 5

 
Sample Output

24120

 因為2009=7*7*41， 所以41及往後的階乘對2009取餘都為0.

#include <stdio.h>int arr[42] = {1, 1};int main(){int i;for(i = 2; i < 42; ++i)arr[i] = (arr[i-1] * i) % 2009;while(scanf("%d", &i) == 1){if(i < 42) printf("%d\n", arr[i]);else printf("0\n");}return 0;}