Pythonleetcode125. 验证回文串

class Solution:
    def isPalindrome(self, s):
        """
        :type s: str
        :rtype: bool
        """
        if(s==" "):
            return True
        str=''
        for i in s:
            if(i.isalpha() or i.isdigit()):
                str=str+i
            else:
                continue
        str=str.lower()
        #print(str)
        return (list(reversed(str))==list(str))