求常数e

//计算阶乘

double Factorial(int n)
{
	if (n == 2)
	{
		return 2.0;
	}
	return n * Factorial(n - 1);
}

//计算常数e
double CalculateE(int n)
{
	if (n == 2)
	{
		return 2.0 + 1.0 / Factorial(2);
	}
	return CalculateE(n - 1) + 1.0 / Factorial(n);
}