Merge pull request #2973 from coopers/0226

Update 0226-invert-binary-tree.py

Author: felivalencia3

python/0226-invert-binary-tree.py

@@ -5,15 +5,14 @@
 #         self.left = left
 #         self.right = right
 class Solution:
-    def invertTree(self, root: TreeNode) -> TreeNode:
+    def invertTree(self, root: Optional[TreeNode]) -> Optional[TreeNode]:
         if not root:
             return None
-
+        
         # swap the children
-        tmp = root.left
-        root.left = root.right
-        root.right = tmp
-
+        root.left, root.right = root.right, root.left
+        
+        # make 2 recursive calls
         self.invertTree(root.left)
         self.invertTree(root.right)
         return root