杭电acm 3132GCC（简单数论）

GCC

Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others)

Total Submission(s): 5140    Accepted Submission(s): 1716


Problem Description

The GNU Compiler Collection (usually shortened to GCC) is a compiler system produced by the GNU Project supporting various programming languages. But it doesn’t contains the math operator “!”.

In mathematics the symbol represents the factorial operation. The expression n! means "the product of the integers from 1 to n". For example, 4! (read four factorial) is 4 × 3 × 2 × 1 = 24. (0! is defined as 1, which is a neutral element in multiplication,
not multiplied by anything.)

We want you to help us with this formation: (0! + 1! + 2! + 3! + 4! + ... + n!)%m

 

Input

The first line consists of an integer T, indicating the number of test cases.

Each test on a single consists of two integer n and m.

 

Output

Output the answer of (0! + 1! + 2! + 3! + 4! + ... + n!)%m.

Constrains

0 < T <= 20

0 <= n < 10^100 (without leading zero)

0 < m < 1000000

 

Sample Input

1
10 861017

 

Sample Output

593846

 

Source

2009 Asia Wuhan Regional Contest Online

想法：

n>m时，比m大的数乘起后对取余m后没影响

代码：

#include<stdio.h>

#include<string.h>

int main()

{

    int i,j,n,m,cas,t;

    long long mid,sum;

    char s[1000];

    scanf("%d",&cas);

    while(cas--)

    {

    scanf("%s %d",&s,&m);

    if(strlen(s)>=7)

    t=m;

    else sscanf(s,"%d",&t);

    mid=1;

    sum=1;

    for(i=1;i<=t;i++)

    {

    mid=(mid*i)%m;

    sum=(sum+mid)%m;

    }

    printf("%lld\n",sum%m);//这里一定一定要%m 否则会错

    }

    return 0;

}