代码

#include <cstdio>
#include <cmath>
#include <ctime>

int calc_1()
{
	int st = clock(), r = 1;
	for (register int i = 1; i <= 1000000; ++i)
	{
		r = r + r;
		r = r - (r >> 1);
	}
	return clock() - st;
}

int calc_2()
{
	int st = clock();
	double n = 1e17, res = 0;
	for (register int i = 1; i <= 1000000; ++i)
	{
		n -= 1;
		res = log(n);
	}
	return clock() - st;
}

int main()
{
	printf("%d %d", calc_2(), calc_2());
	return 0;
}

评测结果