[LeetCode] 125. Valid Palindrome

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

Use two pointers to compare letters from head and tail. And ignore none-alpha-num letter.

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