Time: 42 ms (83.50%), Space: 17.7 MB (73.75%) - LeetHub

0623-add-one-row-to-tree/0623-add-one-row-to-tree.py

@@ -10,16 +10,30 @@ def addOneRow(self, root: Optional[TreeNode], val: int, depth: int) -> Optional[
         if depth == 1:
             return TreeNode(val, root, None)
 
-        elif depth == 2:
-            root.left = TreeNode(val, root.left, None)
-            root.right = TreeNode(val, None, root.right)
-
-        else:
-            if root.left:
-                self.addOneRow(root.left, val, depth - 1)
-            if root.right:
-                self.addOneRow(root.right, val, depth - 1)
+        queue = [root]
 
+        while 0 < len(queue):
+
+            depth -= 1
+
+            count = len(queue)
+
+            for _ in range(count):
+                node = queue.pop(0)
+
+                if node.left is not None:
+                    queue.append(node.left)
+
+                if node.right is not None:
+                    queue.append(node.right)
+
+                if depth == 1:
+                    node.left = TreeNode(val, node.left, None)
+                    node.right = TreeNode(val, None, node.right)
+
+            if depth == 1:
+                break
+
         return root