LeetCode 125 - Valid Palindrome Problem

Problem Statement

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

Note: For the purpose of this problem, we define empty string as valid palindrome.

Example 1:

Input: "A man, a plan, a canal: Panama"
Output: true

Example 2:

Input: "race a car"
Output: false

Solution:

class Solution: def isPalindrome(self, s: str) -> bool: if not s: return True s = s.lower() i=0 j = len(s)-1 while i<j: while not s[i].isalnum() and i<j: i+=1 while not s[j].isalnum() and i<j: j-=1 if s[i]!=s[j]: return False i+=1 j-=1 return True