leetcode-125-验证回文串

题目描述：

方法一：正则

class Solution:
    def isPalindrome(self, s: str) -> bool:
        return ''.join(re.findall('\w*',s)).lower() == ''.join(re.findall('\w*',s)).lower()[::-1]

方法二：

class Solution:
    def isPalindrome(self, s: str) -> bool:
        begin = 0
        end = len(s) - 1
        while begin < end:
            while begin < end and not s[begin].isalnum():
                begin += 1
            while begin < end and not s[end].isalnum():
                end -= 1
            if s[begin].lower() != s[end].lower():
                return False
            begin += 1
            end -= 1
        return True

 方法三：

class Solution:
    def isPalindrome(self, s: str) -> bool:
        s = ''.join(filter(str.isalnum,s)).lower()
        return s==s[::-1]