【练习】回文字符

转载：LeetCode:https://leetcode.cn/problems/valid-palindrome/solution/yan-zheng-hui-wen-chuan-by-leetcode-solution/

"""回文字符
lower（）用来将字符串所有大写转换成小写
''.join 用来将字符串分割
isalnum（）用来检测字符串是否是由字母或数字组成（即不能是空字符串，或者有特殊字符）
"""
# a = "StRiNg111"
# print(''.join(a.lower()))
# 双指针方法
class Solution:
    def isPalindrome(self, s: str) -> bool:
        sgood = ''.join(ch.lower() for ch in s if ch.isalnum())
        n = len(sgood)
        left, right = 0, n-1
        while left < right:
            if sgood[left] != sgood[right]:
                print("False")
                return False
            left, right = left + 1, right - 1
        print("True")
        return True

string = Solution()
string.isPalindrome("mam")