add some fun tree playing

trees_and_graphs/is_tree_symmetric.py

@@ -0,0 +1,38 @@
+def is_symmetrical(root: Optional[TreeNode]) -> bool:
+        
+        stack = [(root, root)]
+        
+        while stack:
+            
+            node1, node2 = stack.pop()
+            
+            if (not node1 and node2) or (not node2 and node1):
+                return False
+            
+            elif not node1 and not node2:
+                continue
+            
+            elif node1 and node2 and node1.val != node2.val:
+                    return False
+            
+            stack.append([node1.left, node2.right])
+            stack.append([node1.right, node2.left])
+        
+        return True
+
+
+def is_symmetrical_recursive(root: Optional[TreeNode]) -> bool:
+            
+            def helper(node1, node2):
+                if (not node1 and node2) or \
+                   (not node2 and node1) or \
+                   (node1 and node2 and node1.val != node2.val):
+                        return False
+                
+                if (not node1 and not node2):
+                        return True
+                
+                return helper(node1.left, node2.right) and helper(node2.left, node1.right)
+            
+            return helper(root.left, root.right)
+