125. Valid Palindrome[Easy].md

• 문제

  A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers.
  
  Given a string s, return true if it is a palindrome, or false otherwise.
  
   
  
  Example 1:
  
  Input: s = "A man, a plan, a canal: Panama"
  Output: true
  Explanation: "amanaplanacanalpanama" is a palindrome.
  Example 2:
  
  Input: s = "race a car"
  Output: false
  Explanation: "raceacar" is not a palindrome.
  Example 3:
  
  Input: s = " "
  Output: true
  Explanation: s is an empty string "" after removing non-alphanumeric characters.
  Since an empty string reads the same forward and backward, it is a palindrome.
   
  
  Constraints:
  
  1 <= s.length <= 2 * 105
  s consists only of printable ASCII characters.

• 나의 풀이

  class Solution:
      def isPalindrome(self, s: str) -> bool:
          s2 = ''.join(c.lower() for c in s if c.isalpha() or c.isnumeric())
          if s2[::-1] == s2:
              return True
          return False