HDU 1042 N!

 1 #include <iostream>
 2 #include <cstring>
 3 using namespace std;
 4 int ans[10000],tmp,n,len;
 5 int main()
 6 {
 7     while(~scanf("%d",&n))
 8     {
 9         memset(ans,0,sizeof(ans));
10         len=ans[1]=1;
11         for(int i=1;i<=n;i++)
12         {
13             tmp=0;
14             for(int j=1;j<=len;j++)
15             {
16                 ans[j]=ans[j]*i+tmp;
17                 tmp=ans[j]/10000;
18                 ans[j]%=10000;
19             }
20             while(tmp)
21             {
22                 ans[++len]=tmp%10000;
23                 tmp/=10000;
24             }
25         }
26         printf("%d",ans[len]);
27         for(int i=len-1;i>0;i--) printf("%04d",ans[i]);
28         puts("");
29     }
30 }