LeetCode 69 - Why int(2.0) equals 1?

Question

My code is as following：

import math
class Solution(object):
    def mySqrt(self, x):
        """
        :type x: int
        :rtype: int
        """
        if x == 0: return 0

        res = pow(math.e, 0.5 * math.log(x))
        print(res)

        return int(res)

This is based on the idea that

When the test case is 4, it's expected to output 2 but it gives 1 back.

I check the value of res which is 2.0.

So what's the problem here?

Answer 1

if you print(repr(res)) you will see that res = 1.9999999999999998 the int of that is indeed 1.

you could return ruound(res) (there is the doc of round) if that suits your use-case.

if your are interested in integer square roots only this wikipedia article may be interesting for you.