（hdu）1042 N! 大数相乘

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
 

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <stack>
#include <queue>
#include <vector>
using namespace std;
#define N 10010
#define met(a,b) memset(a,b,sizeof(a));
vector<vector<int> >Q;
int a[N],n;
void add(int m)
{
    for(int i=0;i<N;i++)
    {
        a[i]=a[i]*m;
    }
    for(int i=0;i<N-1;i++)
    {
        a[i+1]+=a[i]/10000;
        a[i]=a[i]%10000;
    }
}
void put(int a[])
{
    int i=N-1;
    while(!a[i])i--;
    printf("%d",a[i]);
    for(i--;i>=0;i--)
        printf("%04d",a[i]);
    puts("");
}
void init()
{
    a[0]=1;
    for(int i=1;i<=n;i++)
    {
        add(i);
    }
}
int main()
{
    while(scanf("%d",&n)!=EOF)
    {
        if(n==0)
        {
             printf("1\n");
             continue;
        }

        met(a,0);
        init();
        put(a);
    }
    return 0;
}