[C++] 算e 最簡單版!!

int main()
{
    double e=0;
    int size= 20, j;
    for(j=0;j<size;j++)
    {
        int i;
        unsigned long long result=1;
        for(i=1 ; i<=j ; ++i)
    {
        result=result*i;
    }
        e=e+(1.0/result);
        cout<< e << endl;
    }
    cout<<e<<endl;
    return 0;
}