HDU, 2674 N！Again（求N! 09的最大值，n最大10^9）

N！Again

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

24120

 

Author

WhereIsHeroFrom

 

Source

HDU女生专场公开赛——谁说女子不如男

 

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题意：

求N!%2009的最大值，n最大10^9。

解题思路：

乘法分配率。

#include<iostream>#include<cstdio>#include<cmath>using namespace std;int N;int main(){    int ans;    while(cin>>N){        if(N>=2009){            printf("0\n");        }        else{                ans=1;                for(int i=N;i>=1;i--){                    ans=(ans*i)%2009;                }                printf("%d\n",ans);        }    }    return 0;}