Valid Palindrome Python Solution with Tests

lcpy gen -n 125   # by problem number
lcpy gen -s valid_palindrome   # by problem name

Input: s = "A man, a plan, a canal: Panama"
Output: true

Input: s = "race a car"
Output: false

Input: s = " "
Output: true

class Solution:
    # Time: O(n)
    # Space: O(1)
    def is_palindrome(self, s: str) -> bool:
        left, right = 0, len(s) - 1

        while left < right:
            while left < right and not s[left].isalnum():
                left += 1
            while left < right and not s[right].isalnum():
                right -= 1

            if s[left].lower() != s[right].lower():
                return False

            left += 1
            right -= 1

        return True