[leetcood] 125. Valid Palindrome

class Solution:
    def isPalindrome(self, s: str) -> bool:
        # First way
        strs = []
        for char in s:
            if char.isalnum():
                strs.append(char.lower())
        
        # Is Palindrome?
        while len(strs) > 1:
            if strs.pop(0) != strs.pop():
                return False
        
        return True
###################################################################################
        # Second way
        strs: Deque = collections.deque()

        for char in s:
            if char.isalnum():
                strs.append(char.lower())

        while len(strs) > 1:
            if strs.popleft() != strs.pop():
                return False

        return True
###################################################################################
        # Third way
        s = s.lower()
        # 정규식으로 불필요한 문자 필터링
        s = re.sub('[^a-z0-9]', '', s)

        return s == s[::-1]