LeetCode #16: 3Sum Closest

[WazedKhan]

Summary by CodeRabbit

• New Features

  • Added solution implementation for the LeetCode "3Sum Closest" problem

• Tests

  • Added parametrized test cases with multiple scenarios to validate the new solution

[coderabbitai]

📝 Walkthrough

Walkthrough

Adds a new file LeetCode/medium/three_sum_closest_16.py implementing Solution.threeSumClosest using a sort-and-two-pointer approach. A corresponding parametrized pytest block is added to tests/test_leetcode_medium.py to verify correctness across multiple input cases.

Changes

3Sum Closest Solution

Layer / File(s)	Summary
Implementation and tests LeetCode/medium/three_sum_closest_16.py, tests/test_leetcode_medium.py	Solution.threeSumClosest sorts nums, iterates each index as the first element, and uses a two-pointer scan to find and track the three-number sum nearest to target. Tests verify the function against multiple (nums, target, expected) cases.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐇 Hoppity-hop through the sorted array,
Two pointers dancing, they find their way.
Closest to target? I've got the knack!
Left pointer forward, right pointer back.
The rabbit solves sums without delay! 🥕

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'LeetCode #16: 3Sum Closest' clearly and specifically identifies the problem being solved, directly matching the main change of implementing the 3Sum Closest solution.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch leetcode-16-three-sum-closest

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[coderabbitai]

🧹 Nitpick comments (1)

LeetCode/medium/three_sum_closest_16.py (1)

13-17: 🧹 Nitpick | 🔵 Trivial | ⚡ Quick win

Consider early return on exact match.

When three_sum == target, the algorithm has found the closest possible sum (distance = 0). Consider adding an early return for a performance optimization:

⚡ Suggested optimization

             while left < right:
                 three_sum = nums[index] + nums[left] + nums[right]
+                if three_sum == target:
+                    return target
                 if three_sum < target:
                     left += 1

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@LeetCode/medium/three_sum_closest_16.py` around lines 13 - 17, The current
logic in the three_sum closest calculation only checks if three_sum < target or
executes an else clause, but does not explicitly handle the case when three_sum
== target. Since an exact match represents the minimum possible distance (0),
add an early return condition before the existing if three_sum < target check to
return target immediately when three_sum equals target. This optimization avoids
unnecessary iterations when the optimal answer is already found.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Nitpick comments:
In `@LeetCode/medium/three_sum_closest_16.py`:
- Around line 13-17: The current logic in the three_sum closest calculation only
checks if three_sum < target or executes an else clause, but does not explicitly
handle the case when three_sum == target. Since an exact match represents the
minimum possible distance (0), add an early return condition before the existing
if three_sum < target check to return target immediately when three_sum equals
target. This optimization avoids unnecessary iterations when the optimal answer
is already found.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 49c9f56f-d2df-4274-8649-e6530522c914

📥 Commits

Reviewing files that changed from the base of the PR and between 6fa9e51 and 6a8f3ce.

📒 Files selected for processing (2)

• LeetCode/medium/three_sum_closest_16.py
• tests/test_leetcode_medium.py