Given a positive integer num, write a function which returns True if num is a perfect square else False.

Note: Do not use any built-in library function such as sqrt.

Example 1:

Input: 16

Returns: True

Example 2:

Input: 14

Returns: False

Use Newton Method to calculate the square root or num, refer to Newton Method for details.

Code

class Solution:

    def validSquare(self, n):

        ans = n

        while ans * ans > n:

            ans = (ans + n/ans)//2

        return ans **2 == n