feat(trees): height of tree

datastructures/trees/binary/tree/__init__.py

@@ -52,27 +52,15 @@ def height(self) -> int:
         if self.root.left is None and self.root.right is None:
             return 1
 
-        height = 0
-        queue = FifoQueue()
-        queue.enqueue(self.root)
+        def height_helper(current_node: BinaryTreeNode) -> int:
+            if not current_node:
+                return -1
+            left_height = height_helper(current_node.left)
+            right_height = height_helper(current_node.right)
 
-        while True:
-            current_level_nodes = queue.size
+            return 1 + max(left_height, right_height)
 
-            if current_level_nodes == 0:
-                return height
-
-            height += 1
-
-            while current_level_nodes > 0:
-                node = queue.dequeue()
-
-                if node.left is not None:
-                    queue.enqueue(node.left)
-
-                if node.right is not None:
-                    queue.enqueue(node.right)
-                current_level_nodes -= 1
+        return height_helper(self.root)
 
     def has_next(self) -> bool:
         pass

datastructures/trees/binary/tree/test_binary_tree.py

@@ -220,15 +220,14 @@ def test_returns_1_for_root_but_no_children(self):
     def test_returns_3_for_tree_3_9_20_null_null_15_7(self):
         """should return 3 if the binary tree [3,9,20,null,null,15,7]"""
         left = BinaryTreeNode(data=9)
-        right_left = BinaryTreeNode(data=15)
-        right_right = BinaryTreeNode(data=7)
-        right = BinaryTreeNode(data=20, left=right_left, right=right_right)
+        right = BinaryTreeNode(data=20, left=BinaryTreeNode(data=15), right=BinaryTreeNode(data=7))
 
         root = BinaryTreeNode(data=3, left=left, right=right)
         tree = BinaryTree(root=root)
 
         actual = tree.height()
-        self.assertEqual(3, actual)
+        expected = 2
+        self.assertEqual(expected, actual)
 
     def test_returns_2_for_tree_1_null_20(self):
         """should return 2 if the binary tree [1,null,20]"""
@@ -238,7 +237,20 @@ def test_returns_2_for_tree_1_null_20(self):
         tree = BinaryTree(root=root)
 
         actual = tree.height()
-        self.assertEqual(2, actual)
+        expected = 1
+        self.assertEqual(expected, actual)
+
+    def test_returns_2_for_tree_1_2_3_4_5(self):
+        """should return 2 if the binary tree [1,2,3,4,5]"""
+        right = BinaryTreeNode(data=3)
+        left = BinaryTreeNode(data=2, left=BinaryTreeNode(data=4), right=BinaryTreeNode(5))
+
+        root = BinaryTreeNode(data=1, left=left, right=right)
+        tree = BinaryTree(root=root)
+
+        actual = tree.height()
+        expected = 2
+        self.assertEqual(expected, actual)
 
 
 class BinaryTreeLeafSimilarTest(unittest.TestCase):