플리나를 위하여

int Problem002(int first, int second, int scope)
{
	int ret = 0;
	int third = first + second;

	if (first % 2 == 0)
	{
		ret += first;
	}
	if (second % 2 == 0)
	{
		ret += second;
	}

	while (true)
	{
		if (third > scope)
		{
			break;
		}
		if (third % 2 == 0)
		{
			ret += third;
		}
		first = second;
		second = third;
		third = first + second;
	}
	return ret;
}

int num1 = 3, int num2 = 5, int scope = 1000

// 일반적인 구현
int Problem001(int num1, int num2, int scope)
{
	int ret = 0;
	for (int i = 1; i < scope; i++)
	{
		if (i%num1 == 0 || i % num2 == 0)
		{
			ret += i;
		}
	}
	return ret;
}

// 수학 공식을 통한 구현
int Problem001(int num1, int num2, int scope)
{
	scope--;
	return sumUpToScope(num1, scope) + sumUpToScope(num2, scope) - sumUpToScope(num1 * num2, scope);
}

int sumUpToScope(int num, int scope)
{
	return (((1 + (scope / num)) * (scope / num)) / 2) * num;
}