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feat: add lowest_common_ancestor_of_a_binary_tree
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‎.templates/leetcode/json/lowest_common_ancestor_of_a_binary_search_tree.json‎

Lines changed: 3 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -30,24 +30,19 @@
3030
"test_imports": "import pytest\nfrom leetcode_py import TreeNode\nfrom leetcode_py.test_utils import logged_test\nfrom .solution import Solution",
3131
"test_class_name": "LowestCommonAncestorOfABinarySearchTree",
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"test_helper_methods": [
33-
{ "name": "setup_method", "parameters": "", "body": "self.solution = Solution()" },
34-
{
35-
"name": "_find_node",
36-
"parameters": "root: TreeNode[int], val: int",
37-
"body": "if not root:\n return None\nif root.val == val:\n return root\nleft = self._find_node(root.left, val)\nif left:\n return left\nreturn self._find_node(root.right, val)"
38-
}
33+
{ "name": "setup_method", "parameters": "", "body": "self.solution = Solution()" }
3934
],
4035
"test_methods": [
4136
{
4237
"name": "test_lowest_common_ancestor",
4338
"parametrize": "root_list, p_val, q_val, expected_val",
4439
"parametrize_typed": "root_list: list[int | None], p_val: int, q_val: int, expected_val: int",
4540
"test_cases": "[([6, 2, 8, 0, 4, 7, 9, None, None, 3, 5], 2, 8, 6), ([6, 2, 8, 0, 4, 7, 9, None, None, 3, 5], 2, 4, 2), ([2, 1], 2, 1, 2), ([2, 1], 1, 2, 2), ([6, 2, 8, 0, 4, 7, 9], 0, 4, 2), ([6, 2, 8, 0, 4, 7, 9], 7, 9, 8)]",
46-
"body": "root = TreeNode[int].from_list(root_list)\nassert root is not None\np = self._find_node(root, p_val)\nq = self._find_node(root, q_val)\nassert p is not None and q is not None\nresult = self.solution.lowest_common_ancestor(root, p, q)\nassert result is not None\nassert result.val == expected_val"
41+
"body": "root = TreeNode[int].from_list(root_list)\nassert root is not None\np = root.find_node(p_val)\nq = root.find_node(q_val)\nassert p is not None and q is not None\nresult = self.solution.lowest_common_ancestor(root, p, q)\nassert result is not None\nassert result.val == expected_val"
4742
}
4843
],
4944
"playground_imports": "from leetcode_py import TreeNode\nfrom solution import Solution",
5045
"playground_test_case": "# Example test case\nroot_list = [6, 2, 8, 0, 4, 7, 9, None, None, 3, 5]\np_val = 2\nq_val = 8\nexpected_val = 6",
51-
"playground_execution": "root = TreeNode[int].from_list(root_list)\np = find_node(root, p_val)\nq = find_node(root, q_val)\nresult = Solution().lowest_common_ancestor(root, p, q)\nresult.val if result else None",
46+
"playground_execution": "root = TreeNode[int].from_list(root_list)\nassert root is not None\np = root.find_node(p_val)\nq = root.find_node(q_val)\nassert p is not None and q is not None\nresult = Solution().lowest_common_ancestor(root, p, q)\nresult.val if result else None",
5247
"playground_assertion": "assert result and result.val == expected_val"
5348
}

‎.templates/leetcode/json/lowest_common_ancestor_of_a_binary_tree.json‎

Lines changed: 48 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,48 @@
1+
{
2+
"problem_name": "lowest_common_ancestor_of_a_binary_tree",
3+
"solution_class_name": "Solution",
4+
"problem_number": "236",
5+
"problem_title": "Lowest Common Ancestor of a Binary Tree",
6+
"difficulty": "Medium",
7+
"topics": "Tree, Depth-First Search, Binary Tree",
8+
"tags": ["grind-75"],
9+
"readme_description": "Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.\n\nAccording to the definition of LCA on Wikipedia: \"The lowest common ancestor is defined between two nodes `p` and `q` as the lowest node in `T` that has both `p` and `q` as descendants (where we allow **a node to be a descendant of itself**).\"",
10+
"readme_examples": [
11+
{
12+
"content": "<img alt=\"\" src=\"https://assets.leetcode.com/uploads/2018/12/14/binarytree.png\" style=\"width: 200px; height: 190px;\" />\n\n```\nInput: root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 1\nOutput: 3\nExplanation: The LCA of nodes 5 and 1 is 3.\n```"
13+
},
14+
{
15+
"content": "<img alt=\"\" src=\"https://assets.leetcode.com/uploads/2018/12/14/binarytree.png\" style=\"width: 200px; height: 190px;\" />\n\n```\nInput: root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 4\nOutput: 5\nExplanation: The LCA of nodes 5 and 4 is 5, since a node can be a descendant of itself according to the LCA definition.\n```"
16+
},
17+
{ "content": "```\nInput: root = [1,2], p = 1, q = 2\nOutput: 1\n```" }
18+
],
19+
"readme_constraints": "- The number of nodes in the tree is in the range [2, 10^5].\n- -10^9 <= Node.val <= 10^9\n- All Node.val are unique.\n- p != q\n- p and q will exist in the tree.",
20+
"readme_additional": "",
21+
"solution_imports": "from leetcode_py import TreeNode",
22+
"solution_methods": [
23+
{
24+
"name": "lowest_common_ancestor",
25+
"parameters": "root: TreeNode, p: TreeNode, q: TreeNode",
26+
"return_type": "TreeNode",
27+
"dummy_return": "root"
28+
}
29+
],
30+
"test_imports": "import pytest\nfrom leetcode_py.test_utils import logged_test\nfrom leetcode_py import TreeNode\nfrom .solution import Solution",
31+
"test_class_name": "LowestCommonAncestorOfABinaryTree",
32+
"test_helper_methods": [
33+
{ "name": "setup_method", "parameters": "", "body": "self.solution = Solution()" }
34+
],
35+
"test_methods": [
36+
{
37+
"name": "test_lowest_common_ancestor",
38+
"parametrize": "root_list, p_val, q_val, expected_val",
39+
"parametrize_typed": "root_list: list[int | None], p_val: int, q_val: int, expected_val: int",
40+
"test_cases": "[([3,5,1,6,2,0,8,None,None,7,4], 5, 1, 3), ([3,5,1,6,2,0,8,None,None,7,4], 5, 4, 5), ([1,2], 1, 2, 1)]",
41+
"body": "root = TreeNode.from_list(root_list)\nassert root is not None\np = root.find_node(p_val)\nq = root.find_node(q_val)\nassert p is not None and q is not None\nresult = self.solution.lowest_common_ancestor(root, p, q)\nassert result is not None\nassert result.val == expected_val"
42+
}
43+
],
44+
"playground_imports": "from solution import Solution\nfrom leetcode_py import TreeNode",
45+
"playground_test_case": "# Example test case\nroot_list = [3,5,1,6,2,0,8,None,None,7,4]\nroot = TreeNode.from_list(root_list)\nassert root is not None\np = root.find_node(5)\nq = root.find_node(1)\nexpected_val = 3",
46+
"playground_execution": "result = Solution().lowest_common_ancestor(root, p, q)\nresult.val",
47+
"playground_assertion": "assert result.val == expected_val"
48+
}

‎Makefile‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
PYTHON_VERSION = 3.13
2-
PROBLEM ?= product_of_array_except_self
2+
PROBLEM ?= lowest_common_ancestor_of_a_binary_search_tree
33
FORCE ?= 0
44
COMMA := ,
55

‎leetcode/lowest_common_ancestor_of_a_binary_search_tree/playground.ipynb‎

Lines changed: 158 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -2,7 +2,7 @@
22
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5-
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5+
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"outputs": [],
@@ -14,7 +14,7 @@
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},
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{
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"cell_type": "code",
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"execution_count": null,
17+
"execution_count": 2,
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"id": "setup",
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"metadata": {},
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"outputs": [],
@@ -28,21 +28,171 @@
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"execution_count": 3,
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"id": "execute",
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"metadata": {},
34-
"outputs": [],
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"outputs": [
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{
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"data": {
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"text/plain": [
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"6"
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]
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},
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"execution_count": 3,
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"metadata": {},
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"output_type": "execute_result"
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}
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],
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"source": [
3647
"root = TreeNode[int].from_list(root_list)\n",
37-
"p = find_node(root, p_val)\n",
38-
"q = find_node(root, q_val)\n",
48+
"assert root is not None\n",
49+
"p = root.find_node(p_val)\n",
50+
"q = root.find_node(q_val)\n",
51+
"assert p is not None and q is not None\n",
3952
"result = Solution().lowest_common_ancestor(root, p, q)\n",
4053
"result.val if result else None"
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]
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},
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{
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"cell_type": "code",
45-
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58+
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"id": "d84494ee",
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181+
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@@ -65,7 +215,7 @@
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}

‎leetcode/lowest_common_ancestor_of_a_binary_search_tree/tests.py‎

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Original file line numberDiff line numberDiff line change
@@ -10,16 +10,6 @@ class TestLowestCommonAncestorOfABinarySearchTree:
1010
def setup_method(self):
1111
self.solution = Solution()
1212

13-
def _find_node(self, root: TreeNode[int] | None, val: int):
14-
if not root:
15-
return None
16-
if root.val == val:
17-
return root
18-
left = self._find_node(root.left, val)
19-
if left:
20-
return left
21-
return self._find_node(root.right, val)
22-
2313
@pytest.mark.parametrize(
2414
"root_list, p_val, q_val, expected_val",
2515
[
@@ -37,8 +27,8 @@ def test_lowest_common_ancestor(
3727
):
3828
root = TreeNode[int].from_list(root_list)
3929
assert root is not None
40-
p = self._find_node(root, p_val)
41-
q = self._find_node(root, q_val)
30+
p = root.find_node(p_val)
31+
q = root.find_node(q_val)
4232
assert p is not None and q is not None
4333
result = self.solution.lowest_common_ancestor(root, p, q)
4434
assert result is not None

‎leetcode/lowest_common_ancestor_of_a_binary_tree/README.md‎

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Original file line numberDiff line numberDiff line change
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# Lowest Common Ancestor of a Binary Tree
2+
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**Difficulty:** Medium
4+
**Topics:** Tree, Depth-First Search, Binary Tree
5+
**Tags:** grind-75
6+
7+
**LeetCode:** [Problem 236](https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-tree/description/)
8+
9+
## Problem Description
10+
11+
Given a binary tree, find the lowest common ancestor (LCA) of two given nodes in the tree.
12+
13+
According to the definition of LCA on Wikipedia: "The lowest common ancestor is defined between two nodes `p` and `q` as the lowest node in `T` that has both `p` and `q` as descendants (where we allow **a node to be a descendant of itself**)."
14+
15+
## Examples
16+
17+
### Example 1:
18+
19+
<img alt="" src="https://assets.leetcode.com/uploads/2018/12/14/binarytree.png" style="width: 200px; height: 190px;" />
20+
21+
```
22+
Input: root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 1
23+
Output: 3
24+
Explanation: The LCA of nodes 5 and 1 is 3.
25+
```
26+
27+
### Example 2:
28+
29+
<img alt="" src="https://assets.leetcode.com/uploads/2018/12/14/binarytree.png" style="width: 200px; height: 190px;" />
30+
31+
```
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Input: root = [3,5,1,6,2,0,8,null,null,7,4], p = 5, q = 4
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Output: 5
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Explanation: The LCA of nodes 5 and 4 is 5, since a node can be a descendant of itself according to the LCA definition.
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```
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### Example 3:
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```
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Input: root = [1,2], p = 1, q = 2
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Output: 1
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```
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## Constraints
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- The number of nodes in the tree is in the range [2, 10^5].
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- -10^9 <= Node.val <= 10^9
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- All Node.val are unique.
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- p != q
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- p and q will exist in the tree.

‎leetcode/lowest_common_ancestor_of_a_binary_tree/__init__.py‎

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