【leetcode】125. 验证回文串（python）

class Solution:
    def isPalindrome(self, s: str) -> bool:
        res = "".join(ch.lower() for ch in s if ch.isalnum())
        return res == res[::-1]

class Solution:
    def isPalindrome(self, s: str) -> bool:
        lst = []
        for ch in s:
            if ch >= 'a' and ch <= 'z':
                lst.append(ch)
            elif ch >= 'A' and ch <= 'Z':
                lst.append(chr(ord(ch) + 32))
            elif ch >= '0' and ch <= '9':
                lst.append(ch)

        ss = "".join(lst)
        j = len(ss) - 1
        for i in range(len(ss)):
            if ss[i] != ss[j]:
                return False
            j -= 1
        return True