fjnu 1461 Factorials

Description

The factorial of n, (written as n!) is n * (n - 1) * (n - 2) * ... * 2 * 1. 0! = 1 (go lookup the Gamma function to find out why). In this problem, you'll be calculating the factorial of an integer between 0 and 100. 100! has no more than 200 digits.

Input

There are 1 or more lines of input. Each line has a single integer, N, on it, such that 0 <= N <= 100.

Output

For each line of input, your program should print out N!.

Sample Input

850

Sample Output

4032030414093201713378043612608166064768844377641568960512000000000000

KEY：这题是求大整数的阶乘，我是采用先乘后进位的办法，有点慢就是了；

 

Source:

#include<iostream>
using namespace std;

void Factorial(int n)
...{
    int a[210];
    int i,j,k;
    for(i=0;i<=200;i++)
    ...{
        a[i]=0;
    }
    a[1]=1;
    k=1;
    for(i=2;i<=n;i++)
    ...{
        for(j=1;j<=k;j++)
        ...{
            a[j]=a[j]*i;
        }
        for(j=1;j<=k;j++)
        ...{
            a[j+1]+=a[j]/10;
            a[j]=a[j]%10;
        }
        while(a[j]>9)
        ...{
            a[j+1]+=a[j]/10;
            a[j]=a[j]%10;            
            if(a[j+1]>0) j++;
        }
        if(a[j]>0) k=j;
    }
    for(i=k;i>0;i--)
        cout<<a[i];
    cout<<endl;
}

int main()
...{
//    freopen("fjnu_1185.in","r",stdin);
    int n;
    while(cin>>n)
    ...{
        Factorial(n);
    }
    return 0;
}