#include<stdio.h>
int factorial (int n);
int main(){
int n;
scanf("%d",&n);
printf("%d \n",factorial(n));
return 0;
}
int factorial(int n){
int i,fact=1;
for(i=1;i<=n;i++)
fact = fact*i;
return fact;
}
原文：http://www.cnblogs.com/geyang/p/6931973.html