feat: add tree_node

.amazonq/rules/development-rules.md

@@ -13,6 +13,7 @@
 
 - Use snake_case for Python method names (following Python convention)
 - Always include type hints for function parameters and return types
+- Use PEP 585/604 syntax: `list[str]`, `dict[str, int]`, `Type | None`, etc.
 - Add return statements to satisfy type checkers even if unreachable
 - Follow the project's linting rules (black, isort, ruff, mypy)
 
@@ -26,6 +27,13 @@
     - `{parameters}` - method parameters with types
     - `{return_type}` - return type annotation
     - Test case placeholders with actual examples
+- **Template Implementation**: Do NOT implement the Solution class - only provide test cases and structure
+- **Helper Functions/Classes**: If the question relies on underlying helper functions or classes (e.g., TreeNode, ListNode):
+    - First check if implementation already exists in `leetcode_py/common/` directory
+    - If found, import from common module
+    - If not found, create shared implementation in `leetcode_py/common/` for reusable classes
+    - For question-specific helpers, implement directly in the solution file
+- **Update Makefile**: When adding new question, update the default `QUESTION` value in Makefile to the new question name
 - Always use the template structure for consistency
 
 ## File Structure

.codecov.yml

@@ -0,0 +1,8 @@
+coverage:
+    status:
+        project:
+            default:
+                target: 70%
+        patch:
+            default:
+                target: 70%

.github/workflows/ci-test.yml

@@ -4,30 +4,30 @@ on:
     push:
         branches: [main]
     pull_request:
-        branches: [main]
+        types: [opened, synchronize, reopened]
 
 jobs:
     test:
         runs-on: ubuntu-latest
 
         steps:
-            - uses: actions/checkout@v4
+            - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
 
             - name: Set up Python
-              uses: actions/setup-python@v5
+              uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5.6.0
               with:
                   python-version: "3.13"
 
             - name: Install Poetry
-              uses: snok/install-poetry@v1
+              uses: snok/install-poetry@76e04a911780d5b312d89783f7b1cd627778900a # v1.4.1
               with:
                   virtualenvs-create: true
                   virtualenvs-in-project: true
                   installer-parallel: true
 
             - name: Load cached venv
               id: cached-poetry-dependencies
-              uses: actions/cache@v4
+              uses: actions/cache@0400d5f644dc74513175e3cd8d07132dd4860809 # v4.2.4
               with:
                   path: .venv
                   key: venv-${{ runner.os }}-${{ steps.setup-python.outputs.python-version }}-${{ hashFiles('**/poetry.lock') }}

Makefile

@@ -1,9 +1,12 @@
 PYTHON_VERSION = 3.13
-QUESTION ?= two_sum
+QUESTION ?= invert_binary_tree
 
 sync_submodules:
 	git submodule update --init --recursive --remote
 
+# WARNING: Opinionated development setup for macOS + zsh + brew
+# This will install/update many tools: pipx, poetry, pre-commit, etc.
+# Only use if you understand what it does and accept the changes
 setup_dev: sync_submodules
 	chmod +x scripts/shared/python/poetry/setup_dev.sh
 	./scripts/shared/python/poetry/setup_dev.sh \
@@ -42,4 +45,4 @@ test-question:
 		echo "Error: Question '$(QUESTION)' not found in leetcode/ directory"; \
 		exit 1; \
 	fi
-	cd leetcode/$(QUESTION) && poetry run pytest tests.py -v -s
+	poetry run pytest leetcode/$(QUESTION)/tests.py -v -s

README.md

@@ -0,0 +1,59 @@
+# LeetCode Practice Repository 🚀
+
+[![Quality Gate Status](https://sonarcloud.io/api/project_badges/measure?project=wisarootl_leetcode-py&metric=alert_status)](https://sonarcloud.io/summary/new_code?id=wisarootl_leetcode-py)
+[![Security Rating](https://sonarcloud.io/api/project_badges/measure?project=wisarootl_leetcode-py&metric=security_rating)](https://sonarcloud.io/summary/new_code?id=wisarootl_leetcode-py)
+[![Vulnerabilities](https://sonarcloud.io/api/project_badges/measure?project=wisarootl_leetcode-py&metric=vulnerabilities)](https://sonarcloud.io/summary/new_code?id=wisarootl_leetcode-py)
+[![codecov](https://codecov.io/gh/wisarootl/leetcode-py/graph/badge.svg?token=TI97VUIA4Z)](https://codecov.io/gh/wisarootl/leetcode-py)
+[![tests](https://img.shields.io/github/actions/workflow/status/wisarootl/leetcode-py/ci-test.yml?branch=main&label=tests&logo=github)](https://github.com/wisarootl/zerv/actions/workflows/ci-test.yml)
+[![release](https://img.shields.io/github/actions/workflow/status/wisarootl/leetcode-py/cd.yml?branch=main&label=release&logo=github)](https://github.com/wisarootl/zerv/actions/workflows/cd.yml)
+
+Premium LeetCode practice environment with modern Python tooling, beautiful tree visualizations, and comprehensive testing.
+
+## ✨ Features
+
+- **Template-driven development** - Consistent structure for every problem
+- **Beautiful tree visualizations** - Pretty-printed binary trees with anytree
+- **Rich test logging** - `@logged_test` decorator with detailed tracebacks
+- **One-command testing** - `make test-question QUESTION=problem_name`
+- **Code quality** - black, isort, ruff, mypy integration
+- **Modern Python** - PEP 585/604 syntax with full type hints
+
+## 🚀 Quick Start
+
+```bash
+# Run existing problems
+make test-question QUESTION=two_sum
+make test-question QUESTION=invert_binary_tree
+
+# Run all tests
+make test
+```
+
+**Adding new problems**: Use an LLM agent (rules in `.amazonq/rules/development-rules.md`) to automatically create new problems from copied LeetCode problem text using the template structure.
+
+## 🧰 Commands
+
+```bash
+make test-question QUESTION=two_sum  # Test specific problem
+make test                            # Run all tests
+make lint                           # Code quality checks
+```
+
+## 🎨 Example Output
+
+```
+# TreeNode visualization
+4
+├── 2
+│   ├── 1
+│   └── 3
+└── 7
+    ├── 6
+    └── 9
+
+# Test logging
+2024-01-01 10:00:00 | SUCCESS | Got result: [4,7,2,9,6,3,1]
+2024-01-01 10:00:00 | DEBUG   | Test passed! ✨
+```
+
+Perfect for interview preparation with professional-grade tooling and beautiful visualizations.

leetcode/_template/README.md

@@ -2,6 +2,7 @@
 
 **Difficulty:** {DIFFICULTY}
 **Topics:** {TOPICS}
+**Tags:** {TAGS}
 
 ## Problem Description
 
@@ -39,13 +40,5 @@ Output: {OUTPUT_3}
 
 {FOLLOW_UP}
 
-## Solution
-
-```python
-def {method_name}({parameters}):
-    # TODO: Implement solution
-    pass
-```
-
 **Time Complexity:** O(?)
 **Space Complexity:** O(?)

leetcode/_template/solution.py

@@ -2,6 +2,8 @@
 
 
 class Solution:
+    # Time: O(?)
+    # Space: O(?)
     def {method_name}(self, {parameters}) -> {return_type}:
         # TODO: Implement solution
         pass

leetcode/_template/tests.py

@@ -1,5 +1,6 @@
 import pytest
 from loguru import logger
+from leetcode_py.test_utils import logged_test
 from .solution import Solution
 
 
@@ -15,9 +16,9 @@ def setup_method(self):
             ({test_case_3}),
         ],
     )
+    @logged_test
     def test_{method_name}(self, {param_names}):
         logger.info(f"Testing with {input_description}")
         result = self.solution.{method_name}({input_params})
         logger.success(f"Got result: {result}")
         assert result == {expected_param}
-        logger.debug("Test passed! ✨")

leetcode/invert_binary_tree/README.md

@@ -0,0 +1,40 @@
+# 226. Invert Binary Tree
+
+**Difficulty:** Easy
+**Topics:** Tree, Depth-First Search, Breadth-First Search, Binary Tree
+**Tags:** grind-75
+
+## Problem Description
+
+Given the root of a binary tree, invert the tree, and return its root.
+
+## Examples
+
+### Example 1:
+
+```
+Input: root = [4,2,7,1,3,6,9]
+Output: [4,7,2,9,6,3,1]
+```
+
+### Example 2:
+
+```
+Input: root = [2,1,3]
+Output: [2,3,1]
+```
+
+### Example 3:
+
+```
+Input: root = []
+Output: []
+```
+
+## Constraints
+
+- The number of nodes in the tree is in the range [0, 100].
+- -100 <= Node.val <= 100
+
+**Time Complexity:** O(?)
+**Space Complexity:** O(?)

leetcode/invert_binary_tree/solution.py

@@ -0,0 +1,12 @@
+from leetcode_py.tree_node import TreeNode
+
+
+class Solution:
+    # Time: O(n) - visit each node once
+    # Space: O(h) - recursion stack depth equals tree height
+    def invert_tree(self, root: TreeNode | None) -> TreeNode | None:
+        if not root:
+            return root
+
+        root.left, root.right = self.invert_tree(root.right), self.invert_tree(root.left)
+        return root

leetcode/invert_binary_tree/tests.py

@@ -0,0 +1,40 @@
+import pytest
+from loguru import logger
+
+from leetcode_py.test_utils import logged_test
+from leetcode_py.tree_node import TreeNode
+
+from .solution import Solution
+
+
+class TestInvertBinaryTree:
+    def setup_method(self):
+        self.solution = Solution()
+
+    @pytest.mark.parametrize(
+        "input_arr, expected_arr",
+        [
+            ([4, 2, 7, 1, 3, 6, 9], [4, 7, 2, 9, 6, 3, 1]),
+            ([2, 1, 3], [2, 3, 1]),
+            ([], []),
+            ([1], [1]),
+            ([1, 2], [1, None, 2]),
+            ([1, None, 2], [1, 2]),
+            ([1, 2, 3, 4, 5], [1, 3, 2, None, None, 5, 4]),
+            ([3, 9, 20, None, None, 15, 7], [3, 20, 9, 7, 15]),
+        ],
+    )
+    @logged_test
+    def test_invert_tree(self, input_arr: list[int | None], expected_arr: list[int | None]):
+        logger.info(f"Testing with input: {input_arr}")
+        root = TreeNode.from_list(input_arr)
+        if root:
+            logger.debug(f"Input tree:\n{root}")
+
+        result = self.solution.invert_tree(root)
+        result_arr = result.to_list() if result else []
+
+        if result:
+            logger.debug(f"Result tree:\n{result}")
+        logger.success(f"Got result: {result_arr}")
+        assert result_arr == expected_arr

leetcode/two_sum/README.md

@@ -2,6 +2,7 @@
 
 **Difficulty:** Easy
 **Topics:** Array, Hash Table
+**Tags:** grind-75
 
 ## Problem Description
 
@@ -46,17 +47,5 @@ Output: [0,1]
 
 Can you come up with an algorithm that is less than O(n²) time complexity?
 
-## Solution
-
-```python
-def twoSum(nums, target):
-    seen = {}
-    for i, num in enumerate(nums):
-        complement = target - num
-        if complement in seen:
-            return [seen[complement], i]
-        seen[num] = i
-```
-
 **Time Complexity:** O(n)
 **Space Complexity:** O(n)

leetcode/two_sum/solution.py

@@ -2,6 +2,8 @@
 
 
 class Solution:
+    # Time: O(n) - single pass through array
+    # Space: O(n) - hash map stores up to n elements
     def two_sum(self, nums: List[int], target: int) -> List[int]:
         seen: dict[int, int] = {}
         for i, num in enumerate(nums):

leetcode/two_sum/tests.py

@@ -1,6 +1,8 @@
 import pytest
 from loguru import logger
 
+from leetcode_py.test_utils import logged_test
+
 from .solution import Solution
 
 
@@ -16,7 +18,9 @@ def setup_method(self):
             ([3, 3], 6, [0, 1]),
         ],
     )
+    @logged_test
     def test_two_sum(self, nums, target, expected):
+        logger.info(f"Testing with nums: {nums}, target: {target}")
         result = self.solution.two_sum(nums, target)
+        logger.success(f"Got result: {result}")
         assert result == expected
-        logger.success("test")

leetcode_py/test_utils.py

@@ -0,0 +1,20 @@
+from functools import wraps
+
+from loguru import logger
+
+
+def logged_test(func):
+    """Decorator to add consistent logging to test methods."""
+
+    @wraps(func)
+    def wrapper(*args, **kwargs):
+        logger.info("")
+        try:
+            result = func(*args, **kwargs)
+            logger.debug("Test passed! ✨")
+            return result
+        except Exception as e:
+            logger.exception(f"Test failed: {e}")
+            raise
+
+    return wrapper