Valid-palindrome solution

Author: KyrieJ95

valid-palindrome/joon.py

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+import re
+
+
+class Solution:
+    # Time: O(n)
+    # Space: O(1)
+    def isPalindrome(self, s: str) -> bool:
+        # 1. Convert string
+        # Time: O(n)
+        # Space: O(n) since re.sub() will internally use a new string of length n.
+        s = re.sub('[^a-z0-9]', '', s.lower())
+        length = len(s)
+        # 2. Check if the string reads the same forward and backward, one by one.
+        # Time: O(n)
+        # Space: O(1)
+        for i in range(length):
+            if (s[i] != s[length - 1 - i]):
+                return False
+        return True