125. 验证回文串

class Solution:
    def isPalindrome(self, s: str) -> bool:
        s=s.lower()
        result=[]
        for i in s:
            if i.isalnum():
                result.append(i)
        return result==result[::-1]
# 找到数字和字母 然后翻转比较

# 官方的更简洁
class Solution:
    def isPalindrome(self, s: str) -> bool:
        sgood = "".join(ch.lower() for ch in s if ch.isalnum())
        return sgood == sgood[::-1]