class Solution:
  def isPalindrome(self, s: str) -> bool:
    # TODO: Write your code here
    str_array = []
    for char in s:
      if char.isalpha() or char.isdigit():
        str_array.append(char.lower())
    front, back = 0, len(str_array) - 1
    while front < back:
      if str_array[front] != str_array[back]:
        return False
      front += 1
      back -= 1
    return True