feat: add 0220 Valid Palindrome solution

Author: hyogshin

valid-palindrome/hyogshin.py

@@ -0,0 +1,14 @@
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        alnum = []
+        is_pal = True
+        for c in s:
+            if c.isalnum():
+                alnum.append(c.lower())
+        
+        for c in range(len(alnum) // 2):
+            if alnum[c] != alnum[-1 - c]:
+                is_pal = False
+                break
+        
+        return is_pal