leetcode @python 125. Valid Palindrome

题目链接

https://leetcode.com/problems/valid-palindrome/

题目原文

Given a string, determine if it is a palindrome, considering only alphanumeric characters and ignoring cases.

For example,
"A man, a plan, a canal: Panama" is a palindrome.
"race a car" is not a palindrome.

题目大意

给定一个字符串，只考虑其中的数字和字母，忽略符号和大小写，判断是否一个回文串

解题思路

将字母都转成小写，过滤掉里面的符号，翻转字符串后和过滤后的字符串进行判断

代码

class Solution(object):
    def isPalindrome(self, s):
        """
        :type s: str
        :rtype: bool
        """
        st = [c for c in s.lower() if c.isalnum()]

        return st == st[::-1]