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