计算1-1/2+1/3-1/4+...-1/100的几种算法总结

计算1-1/2+1/3-1/4+…-1/100

int main()
{
	//法一：
	double n = 1;
	double sub = 0;
	double trem = 0;
	double q = 1;
	for (n = 1; n < 101; ++n)
	{
		trem = q*(1.0 / n);
		sub = sub + trem;
		q = -q;
	}
	printf("sub=%f\n", sub);
}

int main()
{
	//法二：
	double n = 1;
	double sub = 0;
	double q = 1;
	double trem = 0;
	while (n < 7.0)
	{
		trem = q*(1.0 / n);
		sub = sub + trem;
		q = -q;
		n++;
	}
	printf("sub=%f\n", sub);
}

int main()
{
	//法三（最优）
	int i = 0;
	double sub = 0;
	for (i = 1; i < 101; ++i)
	{
		if (i % 2 == 0)
			sub -= 1.0 / i;
		else
			sub += 1.0 / i;
	}

	printf("sub=%f\n", sub);
}