class Solution(object):
    def isPalindrome(self, s):

        left_bound = 0
        right_bound = len(s) - 1

        if right_bound == 0:
            return True

        while(left_bound < right_bound):

            if not s[left_bound].isalnum():
                left_bound += 1
                continue
            elif not s[right_bound].isalnum():
                right_bound -= 1
                continue

            if s[left_bound].lower() == s[right_bound].lower():
                left_bound += 1
                right_bound -= 1
            else:
                return False


        return True