feat(algorithms, dynamic-programming): house robber 3#185
Merged
BrianLusina merged 1 commit intomainfrom Mar 3, 2026
Merged
Conversation
Contributor
📝 WalkthroughWalkthroughThis pull request introduces House Robber III, a binary tree variant of the classic house robber dynamic programming problem, with three solution approaches (recursion, top-down DP with memoization, bottom-up DP), comprehensive documentation detailing constraints and complexity analyses, and refactored parameterized test suite. Changes
Sequence DiagramsequenceDiagram
participant Client
participant rob_iii_recursion
participant BinaryTreeNode
participant rob_iii_dp_top_down
participant Memo
Client->>rob_iii_recursion: Call with root
rob_iii_recursion->>BinaryTreeNode: Visit node
alt Has left child
rob_iii_recursion->>rob_iii_recursion: Recursively visit left
end
alt Has right child
rob_iii_recursion->>rob_iii_recursion: Recursively visit right
end
rob_iii_recursion-->>Client: Return max robbery amount
Client->>rob_iii_dp_top_down: Call with root
rob_iii_dp_top_down->>Memo: Check if node memoised
alt Memoised
Memo-->>rob_iii_dp_top_down: Return cached result
else Not memoised
rob_iii_dp_top_down->>BinaryTreeNode: Visit node
rob_iii_dp_top_down->>rob_iii_dp_top_down: Recursively visit children
rob_iii_dp_top_down->>Memo: Store result
end
rob_iii_dp_top_down-->>Client: Return max robbery amount
Estimated code review effort🎯 3 (Moderate) | ⏱️ ~30 minutes Suggested labels
Poem
🚥 Pre-merge checks | ✅ 2 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (2 passed)
✏️ Tip: You can configure your own custom pre-merge checks in the settings. ✨ Finishing Touches
🧪 Generate unit tests (beta)
Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out. Comment |
BrianLusina
added
enhancement
Algorithm
![coderabbitai[bot]](https://avatars.githubusercontent.com/in/347564?s=60&v=4){kind=small}
Contributor
There was a problem hiding this comment.
Actionable comments posted: 1
🧹 Nitpick comments (2)
algorithms/dynamic_programming/house_robber/test_house_robber.py (1)
20-127: Prefer factory-built trees per case to avoid shared mutable fixtures.
ROB_III_TEST_CASEScurrently reuses the sameBinaryTreeNodeinstances across multiple tests. Generating a fresh tree per case will keep tests isolated and future-proof against accidental node mutation.🧪 Suggested pattern
-ROB_III_TEST_CASES = [ - (BinaryTreeNode(...), 7), -] +ROB_III_TEST_CASES = [ + (lambda: BinaryTreeNode(...), 7), +] `@parameterized.expand`(ROB_III_TEST_CASES) -def test_rob_iii_recursion(self, root: BinaryTreeNode, expected: int): +def test_rob_iii_recursion(self, root_factory, expected: int): + root = root_factory() actual = rob_iii_recursion(root)🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed. In `@algorithms/dynamic_programming/house_robber/test_house_robber.py` around lines 20 - 127, ROB_III_TEST_CASES currently constructs BinaryTreeNode objects once and reuses those same node instances across cases; instead, make each case produce a fresh tree by replacing concrete BinaryTreeNode constructions with factory callables (e.g., lambdas or small helper functions) that return a new BinaryTreeNode root when invoked. Update ROB_III_TEST_CASES to store tuples like (lambda: BinaryTreeNode(...), expected) and change the test harness to call the factory before passing the tree into the functions under test so each run gets a newly-built tree; reference the ROB_III_TEST_CASES symbol and BinaryTreeNode constructors when implementing the factories.algorithms/dynamic_programming/house_robber/README.md (1)
36-36: Polish wording for consistency in two places.Line 36: use “directly linked” (no hyphen).
Line 79: use “Top-Down” to match the section heading style.✏️ Suggested markdown edits
- in this place form a binary tree. It will automatically contact the police if two directly-linked houses were broken + in this place form a binary tree. It will automatically contact the police if two directly linked houses were broken - 2. [Dynamic Programming(Memoization) - Top Down Approach](`#dynamic-programmingmemoization-top-down-approach`) + 2. [Dynamic Programming(Memoization) - Top-Down Approach](`#dynamic-programmingmemoization-top-down-approach`)Also applies to: 79-79
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed. In `@algorithms/dynamic_programming/house_robber/README.md` at line 36, Update the wording for consistency: replace the hyphenated phrase "directly-linked" with "directly linked" in the sentence "It will automatically contact the police if two directly-linked houses were broken" (look for that exact sentence in the README) and change the section/phrase "Top down" to title-case "Top-Down" to match the section heading style (search for "Top down" around the Top-Down section header).
🤖 Prompt for all review comments with AI agents
Verify each finding against the current code and only fix it if needed.
Inline comments:
In `@algorithms/dynamic_programming/house_robber/__init__.py`:
- Around line 17-80: All three functions (rob_iii_recursion,
rob_iii_dynamic_programming_top_down, rob_iii_dynamic_programming_bottom_up) can
crash on skewed trees due to Python recursion limits; add a recursion-depth
guard and a non-recursive fallback: detect current recursion depth (pass a depth
counter or check sys.getrecursionlimit() vs current frame depth) and when depth
approaches the limit (e.g. > 900) switch to an iterative implementation that
uses an explicit stack/post-order traversal with a memo dict (key by node id or
node reference) to compute the same include/exclude values (for bottom_up
compute [include, exclude] per node iteratively; for top_down perform memoized
DFS with an explicit stack or simulate recursion using a stack of frames), and
have rob_iii_recursion call the top_down or bottom_up iterative fallback so all
three handle deep/skewed trees without RecursionError.
---
Nitpick comments:
In `@algorithms/dynamic_programming/house_robber/README.md`:
- Line 36: Update the wording for consistency: replace the hyphenated phrase
"directly-linked" with "directly linked" in the sentence "It will automatically
contact the police if two directly-linked houses were broken" (look for that
exact sentence in the README) and change the section/phrase "Top down" to
title-case "Top-Down" to match the section heading style (search for "Top down"
around the Top-Down section header).
In `@algorithms/dynamic_programming/house_robber/test_house_robber.py`:
- Around line 20-127: ROB_III_TEST_CASES currently constructs BinaryTreeNode
objects once and reuses those same node instances across cases; instead, make
each case produce a fresh tree by replacing concrete BinaryTreeNode
constructions with factory callables (e.g., lambdas or small helper functions)
that return a new BinaryTreeNode root when invoked. Update ROB_III_TEST_CASES to
store tuples like (lambda: BinaryTreeNode(...), expected) and change the test
harness to call the factory before passing the tree into the functions under
test so each run gets a newly-built tree; reference the ROB_III_TEST_CASES
symbol and BinaryTreeNode constructors when implementing the factories.
ℹ️ Review info
Configuration used: Organization UI
Review profile: CHILL
Plan: Pro
⛔ Files ignored due to path filters (20)
algorithms/dynamic_programming/house_robber/images/examples/house_robber_3_example_1.1.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/examples/house_robber_3_example_1.2.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/examples/house_robber_3_example_1.3.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/examples/house_robber_3_example_1.4.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/examples/house_robber_3_example_1.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/examples/house_robber_3_example_2.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/examples/house_robber_3_example_3.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/examples/house_robber_3_example_4.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/solutions/house_robber_iii_solution_dp_bottom_up_1.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/solutions/house_robber_iii_solution_dp_bottom_up_10.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/solutions/house_robber_iii_solution_dp_bottom_up_11.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/solutions/house_robber_iii_solution_dp_bottom_up_12.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/solutions/house_robber_iii_solution_dp_bottom_up_2.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/solutions/house_robber_iii_solution_dp_bottom_up_3.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/solutions/house_robber_iii_solution_dp_bottom_up_4.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/solutions/house_robber_iii_solution_dp_bottom_up_5.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/solutions/house_robber_iii_solution_dp_bottom_up_6.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/solutions/house_robber_iii_solution_dp_bottom_up_7.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/solutions/house_robber_iii_solution_dp_bottom_up_8.pngis excluded by!**/*.pngalgorithms/dynamic_programming/house_robber/images/solutions/house_robber_iii_solution_dp_bottom_up_9.pngis excluded by!**/*.png
📒 Files selected for processing (3)
algorithms/dynamic_programming/house_robber/README.mdalgorithms/dynamic_programming/house_robber/__init__.pyalgorithms/dynamic_programming/house_robber/test_house_robber.py
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Describe your change:
House robber 3 dynamic programming with binary tree
Checklist:
Fixes: #{$ISSUE_NO}.Summary by CodeRabbit
Release Notes
New Features
Documentation
Tests