319. Bulb Switcher - LeetCode

from math import isqrt


class Solution:
    def bulbSwitch(self, n: int) -> int:
        '''
        -> find the amount number of intergers that have odd number of factors
        -> only the square numbers have odd number of factors
        -> find the max number that number's square <= n
        '''
        for i in range(n):
            if (i + 1) ** 2 > n:
                return i
        return n


class Solution0:
    def bulbSwitch(self, n: int) -> int:
        return int(n**0.5)


class Solution2:
    def bulbSwitch(self, n: int) -> int:
        return isqrt(n)