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fix(searches): fix out-of-bounds in single-row and single-column in BinarySearch2dArray - #7724

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hardikkaurani:fix/binary-search-2d-array-bounds
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hardikkaurani wants to merge 1 commit into
TheAlgorithms:masterfrom
hardikkaurani:fix/binary-search-2d-array-bounds

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@hardikkaurani

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  • I have read CONTRIBUTING.md.
  • This pull request is all my own work -- I have not plagiarized it.
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Description

This pull request fixes out-of-bounds errors on single-row and single-column matrices, and exposes binarySearch as a public method in BinarySearch2dArray:

  1. Single-Row Upper Bound Fix: In binarySearch(int[][] arr, int target), when rowCount == 1, the helper binarySearch(arr, target, 0, 0, colCount) was called with colCount instead of colCount - 1. Because the helper uses an inclusive upper bound (colStart <= colEnd), searching for an element greater than arr[0][colCount - 1] caused midIndex to equal colCount, triggering an ArrayIndexOutOfBoundsException. Updated to pass colCount - 1.
  2. Single-Column Handling: When colCount == 1, midCol is 0. Accessing midCol - 1 threw ArrayIndexOutOfBoundsException: Index -1 out of bounds for length 1. Added an edge-case guard returning {-1, -1} when colCount == 1 after checking midCol.
  3. Public API Visibility: Changed binarySearch(int[][] arr, int target) from package-private to public static.
  4. Expanded Tests: Added unit tests covering single-row searches where target is absent (greater than last, smaller than first), single-column searches (present and absent), and single-element 2D arrays.

Copilot AI balanced review requested due to automatic review settings November 2, 2026 05:58

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@hardikkaurani

hardikkaurani commented Nov 2, 2026 •

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Hi @DenizAltunkapan,

Could you please review this pull request when you have a moment?

Summary of Changes

  • Single-Row Bound Fix: Updated binarySearch(arr, target, 0, 0, colCount) to pass colCount - 1, since colEnd is inclusive (colStart <= colEnd). This prevents an ArrayIndexOutOfBoundsException when searching for an element greater than the last element in a single-row array.
  • Single-Column Matrix Handling: Added a guard that returns {-1, -1} when colCount == 1, after checking midCol, preventing negative index access through midCol - 1.
  • Visibility: Changed binarySearch(int[][] arr, int target) to public static.
  • Test Coverage: Added tests for single-row arrays with absent elements, single-column matrices, and single-element matrices. All 17 unit tests pass.

Thank you for your time and consideration!

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.23%. Comparing base (8b49bc5) to head (ca45522).

Additional details and impacted files
@@            Coverage Diff            @@
##             master    #7724   +/-   ##
=========================================
  Coverage     82.23%   82.23%           
- Complexity     8402     8405    +3     
=========================================
  Files           843      843           
  Lines         26140    26142    +2     
  Branches       5100     5101    +1     
=========================================
+ Hits          21495    21497    +2     
- Misses         3853     3854    +1     
+ Partials        792      791    -1     

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3 participants