---
tags: data_structure_python
---

# Valid Palindrome <img src="https://img.shields.io/badge/-easy-brightgreen">

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.

<ins>**Example 1:**</ins>

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

<ins>**Example 2:**</ins>

Input: "race a car"
Output: false

# Solution

class Solution:
    def isPalindrome(self, s: str) -> bool:
        
        s = "".join(elt for elt in s if elt.isalnum()).lower()
        pointer1 = 0
        pointer2 = len(s)-1
        
        while pointer1 < pointer2:
            if s[pointer1] != s[pointer2]:
                return False
            else:
                pointer1 += 1
                pointer2 -= 1
        
        return True