程序代码：

#include<stdio.h>
#define Max 12345
int main()

 {
   
     int wei[Max],jinwei[Max];
     int i,j,n,k,top=1;
          wei[1]=1;
     printf("please input a number:\n");
     scanf("%d",&n);
     for(i=2;i<=n;i++)
     {
         for(j=1;j<=top;j++)
           {
               jinwei[j]=(wei[j]*i+jinwei[j-1])/10;
               wei[j]=(wei[j]*i+jinwei[j-1])%10;
               if(jinwei[top]>=1)
                  {
                    top++;
                  }
            }
     }
      for(k=top;k>=1;k--)
     {
        printf("%d",wei[k]);
     }
     getchar();getchar();

 }