hdu 1042 N!

Problem Description

Given an integer N(0 ≤ N ≤ 10000), your task is to calculate N!

 

 

Input

One N in one line, process to the end of file.

 

 

Output

For each N, output N! in one line.

 

 

Sample Input

1

2

3

 

Sample Output

1

2

6

 高精度运算

#include<stdio.h>
#include<string.h>
int m=10000;
struct bignum{
    int s[20001];//存放结果
    int l;//数组的长度
}a;
bignum operator*(bignum a,int b)//a=a*b
{
    int i;
    for(i=0;i<a.l;i++) a.s[i]*=b;//a的各位数乘b
    for(i=0;i<a.l;i++)
    {
        a.s[i+1]+=a.s[i]/m;
        a.s[i]%=m;
    }
    while(a.s[a.l]!=0)//处理a的最高位
    {
        a.s[a.l+1]+=a.s[a.l]/m;
        a.s[a.l]=a.s[a.l]%m;
        a.l++;
    }
    while(a.s[a.l-1]==0) a.l--;
    return a;
}
void print(bignum a)
{
    printf("%d",a.s[a.l-1]);
    for(int i=a.l-2;i>=0;i--)
        printf("%04d",a.s[i]);
    printf("\n");
}
int main()
{
    int n;
    while(scanf("%d",&n)!=EOF)
    {
        int i;
        memset(a.s,0,sizeof(a.s));
        a.s[0]=1;a.l=1;
        for(i=1;i<=n;i++)
        {
            a=a*i;
        }
        print(a);
    }
    return 0;
}