feat(algorithms, intervals): car pooling

[BrianLusina]

Describe your change:

Car pooling

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized.
• I know that pull requests will not be merged if they fail the automated tests.
• This PR only changes one algorithm file. To ease review, please open separate PRs for separate algorithms.
• All new Python files are placed inside an existing directory.
• All filenames are in all lowercase characters with no spaces or dashes.
• All functions and variable names follow Python naming conventions.
• All function parameters and return values are annotated with Python type hints.
• All functions have doctests that pass the automated testing.
• All new algorithms have a URL in its comments that points to Wikipedia or other similar explanation.
• If this pull request resolves one or more open issues then the commit message contains Fixes: #{$ISSUE_NO}.

Summary by CodeRabbit

• New Features

  • Added car-pooling functionality to the intervals module with two algorithmic approaches to validate passenger capacity over trips.

• Documentation

  • Added a comprehensive guide describing the car-pooling problem, solution approaches, complexity analysis, and illustrative examples.

• Tests

  • Added a test suite covering multiple scenarios to validate both car-pooling implementations produce expected results.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

Caution

Review failed

The pull request is closed.

📝 Walkthrough

Walkthrough

Adds a new Car Pooling problem under algorithms/intervals with two algorithm implementations (event-based and fixed-size timeline) plus documentation and parameterized tests to validate both implementations.

Changes

Cohort / File(s)	Summary
Directory index DIRECTORY.md	Added a Car Pooling subsection entry linking to the new test and module.
Implementation algorithms/intervals/car_pooling/__init__.py	Added car_pooling(trips: List[List[int]], capacity: int) -> bool (event sorting) and car_pooling_bucket(trips: List[List[int]], capacity: int) -> bool (fixed-size timeline/difference array).
Documentation algorithms/intervals/car_pooling/README.md	New README describing the problem, constraints, timeline/difference-array solution, complexity notes, and examples.
Tests algorithms/intervals/car_pooling/test_car_pooling.py	New parameterized test module with CAR_POOLING_TEST_CASES and CarPoolingTestCases verifying both implementations produce expected boolean results.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 I hopped along a winding road,
Counting seats where passengers go,
Events and timelines guide my way,
No overflow on this bright day,
Hooray — the car fits all, hip-hip-hooray! 🚗✨

Pre-merge checks and finishing touches

❌ Failed checks (1 warning, 1 inconclusive)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%.	You can run @coderabbitai generate docstrings to improve docstring coverage.
Description check	❓ Inconclusive	The PR description follows the repository template with all sections completed. However, multiple checklist items have conflicting selections (marking 'Add an algorithm' AND 'Fix a bug' AND 'Documentation change' when only one should apply) and lacks detailed explanation of the actual changes.	Clarify which checkbox(es) actually apply and provide a more detailed description of the car pooling algorithm implementation and its approach.

✅ Passed checks (1 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'feat(algorithms, intervals): car pooling' clearly summarizes the main change - adding a car pooling algorithm to the intervals section.

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📜 Recent review details

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 3b1f7f2 and 5aece96.

📒 Files selected for processing (1)

• algorithms/intervals/car_pooling/__init__.py

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[coderabbitai]

Actionable comments posted: 1

🧹 Nitpick comments (1)

algorithms/intervals/car_pooling/__init__.py (1)

43-60: Add docstring for consistency.

The car_pooling_bucket function lacks a docstring, which is inconsistent with the car_pooling function. Adding a docstring will improve code documentation and maintainability.

🔎 Proposed docstring

 def car_pooling_bucket(trips: List[List[int]], capacity: int) -> bool:
+    """
+    Calculates and checks whether it is possible to pick up and drop off passengers using a timeline-based approach.
+    This implementation uses a fixed-size array (bucket sort) to track passenger changes at each location.
+    
+    Args:
+        trips(list): The trips that the car makes while collecting passengers on the route
+        capacity(int): capacity of the car
+    Returns:
+        bool: whether it is possible to collect and drop all passengers along the route
+    """
     # Initialize a timeline to track changes in passenger count at each km mark (0 to 1000)
     timestamp = [0] * 1001

📜 Review details

Configuration used: defaults

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between dd14168 and 3b1f7f2.

⛔ Files ignored due to path filters (15)

• algorithms/intervals/car_pooling/images/examples/car_pooling_example_1.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/examples/car_pooling_example_2.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/examples/car_pooling_example_3.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/solutions/car_pooling_solution_1.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/solutions/car_pooling_solution_10.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/solutions/car_pooling_solution_11.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/solutions/car_pooling_solution_12.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/solutions/car_pooling_solution_2.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/solutions/car_pooling_solution_3.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/solutions/car_pooling_solution_4.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/solutions/car_pooling_solution_5.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/solutions/car_pooling_solution_6.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/solutions/car_pooling_solution_7.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/solutions/car_pooling_solution_8.png is excluded by !**/*.png
• algorithms/intervals/car_pooling/images/solutions/car_pooling_solution_9.png is excluded by !**/*.png

📒 Files selected for processing (4)

• DIRECTORY.md
• algorithms/intervals/car_pooling/README.md
• algorithms/intervals/car_pooling/__init__.py
• algorithms/intervals/car_pooling/test_car_pooling.py

🧰 Additional context used

🧬 Code graph analysis (1)

algorithms/intervals/car_pooling/test_car_pooling.py (1)

algorithms/intervals/car_pooling/__init__.py (2)

• car_pooling (4-40)
• car_pooling_bucket (43-60)

🪛 LanguageTool

algorithms/intervals/car_pooling/README.md

[style] ~10-~10: This phrase is redundant. Consider writing “point” or “time”.
Context: ...out exceeding the car’s capacity at any point in time. Return TRUE if all trips can be compl...

(MOMENT_IN_TIME)

---

[style] ~33-~33: This phrase is redundant. Consider writing “points” or “times”.
Context: ...e focus on events happening at specific points in time, rather than handling each trip separat...

(MOMENT_IN_TIME)

🪛 markdownlint-cli2 (0.18.1)

DIRECTORY.md

109-109: Unordered list indentation
Expected: 2; Actual: 4

(MD007, ul-indent)

---

110-110: Unordered list indentation
Expected: 4; Actual: 6

(MD007, ul-indent)

🔇 Additional comments (3)

algorithms/intervals/car_pooling/README.md (1)

1-97: LGTM! Comprehensive documentation.

The README provides a thorough explanation of the car pooling problem, including constraints, examples, solution approach, and complexity analysis. The documentation is well-structured and will help developers understand the algorithm.

DIRECTORY.md (1)

109-110: LGTM! Directory entry added correctly.

The Car Pooling entry has been added to the Intervals section following the existing directory structure.

algorithms/intervals/car_pooling/test_car_pooling.py (1)

1-34: LGTM! Comprehensive test coverage.

The test suite provides thorough coverage with diverse test cases covering various scenarios:

• Edge cases (capacity exactly matching requirements)
• Failure cases (capacity exceeded)
• Success cases (capacity sufficient)
• Overlapping trips
• Sequential trips

Both implementations are tested with the same test cases, ensuring consistency.