125. Valid Palindrome

• categories: Code, Interview Question, leetcode, Easy
• source: https://leetcode.com/problems/valid-palindrome/description/
• topics: Two Pointers

A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers.

Given a string s, return true if it is a palindrome, or false otherwise.

class Solution(object):
    def isPalindrome(self, s):
        """
        :type s: str
        :rtype: bool
        """
        i = 0
        j = len(s)-1
        while i < j:
            if not s[i].isalnum():
                i += 1
                continue
            if not s[j].isalnum():
                j -= 1
                continue
            if s[i].lower() != s[j].lower():
                return False
            i += 1
            j -= 1 
        return True