feat: implement isPalindrome function with detailed comments on approach and complexity in python

Author: hongseoupyun

valid-palindrome/hongseoupyun.py

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+# Palindrome is a word, phrase, number, or other sequences of characters that reads the same forward and backward (ignoring non-alphanumeric characters - letters and number).
+# the solution should first filter out non-alphanumeric characters and convert the string to lowercase.
+# Then, it should check if the cleaned string is equal to its reverse.
+
+# Time complexity = O(n), as it checks, replaces, converts to lowercase, and reverses all characters in the string
+# Space complexity = O(n), as it creates a new string with a maximum length equal to the original string
+import re
+
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        filtered_string = re.sub(r'[^a-zA-Z0-9]','',s).lower()
+        reversed_string = filtered_string[::-1]
+        return reversed_string == filtered_string