add solution: valid-palindrome

Author: dusunax

valid-palindrome/dusunax.py

@@ -0,0 +1,28 @@
+'''
+# Leetcode 125. Valid Palindrome
+
+use regex to filter out non-alphanumeric characters 🔍
+
+## Time and Space Complexity
+
+```
+TC: O(n)
+SC: O(n)
+```
+
+### TC is O(n):
+- iterating through the string just once to filter out non-alphanumeric characters.
+
+### SC is O(n):
+- creating a new string to store the filtered characters.
+'''
+
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        if s is " ":
+            return True
+
+        reg = "[^a-z0-9]"
+        converted_s = re.sub(reg, "", s.lower())
+
+        return converted_s == converted_s[::-1]