the power of compile computation

#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
template<int N>
class aTMP{
public:
    enum { 
        ret = N * aTMP<N-1>::ret 
    };
};
template<>
class aTMP<0>{
public:
    enum { 
        ret = 1 
    };
};
long fun(int n) {
    long s = 1;
    for (int i = 2;i <= n;i++) {
        s *= i;
    }
    return s;
}
int main() {
//  cout << aTMP<12>::ret << endl;
//  cout << fun(12) << endl;
    for (int i = 0;i < 1000000;i++) {
        //aTMP<12>::ret;      // 0.011~0.012s
        fun(12);              // 0.044s
    }
    return 0;
}