feat: add Balanced Binary Tree

Author: wislertt

.templates/leetcode/json/balanced_binary_tree.json

@@ -0,0 +1,48 @@
+{
+    "problem_name": "balanced_binary_tree",
+    "solution_class_name": "Solution",
+    "problem_number": "110",
+    "problem_title": "Balanced Binary Tree",
+    "difficulty": "Easy",
+    "topics": "Tree, Depth-First Search, Binary Tree",
+    "tags": ["grind-75"],
+    "readme_description": "Given a binary tree, determine if it is **height-balanced**.\n\nA height-balanced binary tree is a binary tree in which the depth of the two subtrees of every node never differs by more than one.",
+    "readme_examples": [
+        {
+            "content": "![Example 1](https://assets.leetcode.com/uploads/2020/10/06/balance_1.jpg)\n\n```\nInput: root = [3,9,20,null,null,15,7]\nOutput: true\n```"
+        },
+        {
+            "content": "![Example 2](https://assets.leetcode.com/uploads/2020/10/06/balance_2.jpg)\n\n```\nInput: root = [1,2,2,3,3,null,null,4,4]\nOutput: false\n```"
+        },
+        { "content": "```\nInput: root = []\nOutput: true\n```" }
+    ],
+    "readme_constraints": "- The number of nodes in the tree is in the range `[0, 5000]`.\n- `-10^4 <= Node.val <= 10^4`",
+    "readme_additional": "",
+    "solution_imports": "from leetcode_py import TreeNode",
+    "solution_methods": [
+        {
+            "name": "is_balanced",
+            "parameters": "root: TreeNode | None",
+            "return_type": "bool",
+            "dummy_return": "False"
+        }
+    ],
+    "test_imports": "import pytest\nfrom leetcode_py.test_utils import logged_test\nfrom leetcode_py import TreeNode\nfrom .solution import Solution",
+    "test_class_name": "BalancedBinaryTree",
+    "test_helper_methods": [
+        { "name": "setup_method", "parameters": "", "body": "self.solution = Solution()" }
+    ],
+    "test_methods": [
+        {
+            "name": "test_is_balanced",
+            "parametrize": "root_list, expected",
+            "parametrize_typed": "root_list: list[int | None], expected: bool",
+            "test_cases": "[([3, 9, 20, None, None, 15, 7], True), ([1, 2, 2, 3, 3, None, None, 4, 4], False), ([], True)]",
+            "body": "root = TreeNode.from_list(root_list)\nresult = self.solution.is_balanced(root)\nassert result == expected"
+        }
+    ],
+    "playground_imports": "from solution import Solution\nfrom leetcode_py import TreeNode",
+    "playground_test_case": "# Example test case\nroot_list = [3, 9, 20, None, None, 15, 7]\nroot = TreeNode.from_list(root_list)\nexpected = True",
+    "playground_execution": "result = Solution().is_balanced(root)\nresult",
+    "playground_assertion": "assert result == expected"
+}

Makefile

@@ -1,5 +1,5 @@
 PYTHON_VERSION = 3.13
-PROBLEM ?= valid_parentheses
+PROBLEM ?= balanced_binary_tree
 FORCE ?= 0
 COMMA := ,
 

leetcode/balanced_binary_tree/README.md

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+# Balanced Binary Tree
+
+**Difficulty:** Easy
+**Topics:** Tree, Depth-First Search, Binary Tree
+**Tags:** grind-75
+
+**LeetCode:** [Problem 110](https://leetcode.com/problems/balanced-binary-tree/description/)
+
+## Problem Description
+
+Given a binary tree, determine if it is **height-balanced**.
+
+A height-balanced binary tree is a binary tree in which the depth of the two subtrees of every node never differs by more than one.
+
+## Examples
+
+### Example 1:
+
+![Example 1](https://assets.leetcode.com/uploads/2020/10/06/balance_1.jpg)
+
+```
+Input: root = [3,9,20,null,null,15,7]
+Output: true
+```
+
+### Example 2:
+
+![Example 2](https://assets.leetcode.com/uploads/2020/10/06/balance_2.jpg)
+
+```
+Input: root = [1,2,2,3,3,null,null,4,4]
+Output: false
+```
+
+### Example 3:
+
+```
+Input: root = []
+Output: true
+```
+
+## Constraints
+
+- The number of nodes in the tree is in the range `[0, 5000]`.
+- `-10^4 <= Node.val <= 10^4`

leetcode/balanced_binary_tree/__init__.py

@@ -0,0 +1,171 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": 1,
+   "id": "imports",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from solution import Solution\n",
+    "\n",
+    "from leetcode_py import TreeNode"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 2,
+   "id": "setup",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Example test case\n",
+    "root_list = [3, 9, 20, None, None, 15, 7]\n",
+    "root = TreeNode.from_list(root_list)\n",
+    "expected = True"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 3,
+   "id": "f76011d0",
+   "metadata": {},
+   "outputs": [
+    {
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+       "</g>\n",
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+       "</svg>\n"
+      ],
+      "text/plain": [
+       "TreeNode([3, 9, 20, None, None, 15, 7])"
+      ]
+     },
+     "execution_count": 3,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "root"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 4,
+   "id": "execute",
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "True"
+      ]
+     },
+     "execution_count": 4,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "result = Solution().is_balanced(root)\n",
+    "result"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 5,
+   "id": "test",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "assert result == expected"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "leetcode-py-py3.13",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
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+   "nbconvert_exporter": "python",
+   "pygments_lexer": "ipython3",
+   "version": "3.13.7"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}

leetcode/balanced_binary_tree/playground.ipynb

@@ -0,0 +1,20 @@
+from leetcode_py import TreeNode
+
+
+class Solution:
+    # Time: O(n)
+    # Space: O(h)
+    def is_balanced(self, root: TreeNode | None) -> bool:
+        def height(node: TreeNode | None) -> int:
+            if not node:
+                return 0
+
+            left = height(node.left)
+            right = height(node.right)
+
+            if left == -1 or right == -1 or abs(left - right) > 1:
+                return -1
+
+            return max(left, right) + 1
+
+        return height(root) != -1

leetcode/balanced_binary_tree/solution.py

@@ -0,0 +1,33 @@
+import pytest
+
+from leetcode_py import TreeNode
+from leetcode_py.test_utils import logged_test
+
+from .solution import Solution
+
+
+class TestBalancedBinaryTree:
+    def setup_method(self):
+        self.solution = Solution()
+
+    @pytest.mark.parametrize(
+        "root_list, expected",
+        [
+            ([3, 9, 20, None, None, 15, 7], True),
+            ([1, 2, 2, 3, 3, None, None, 4, 4], False),
+            ([], True),
+            ([1], True),
+            ([1, 2], True),
+            ([1, None, 2], True),
+            ([1, 2, 3], True),
+            ([1, 2, None, 3], False),
+            ([1, None, 2, None, 3], False),
+            ([1, 2, 3, 4, 5, 6, 7], True),
+            ([1, 2, 3, 4, None, None, 7, 8], False),
+        ],
+    )
+    @logged_test
+    def test_is_balanced(self, root_list: list[int | None], expected: bool):
+        root = TreeNode.from_list(root_list)
+        result = self.solution.is_balanced(root)
+        assert result == expected