I found a bug in your code in your book. The following code: // Recursive Approach function binarySearch(arr, val, start = 0, end = arr. { const middleIndex = Math.floor((start + end) / 2); if (val === arr[middleIndex]) { return middleIndex; } if (start >= end) { return -1; } if (val = end) { return -1; } if (val < arr[middleIndex]) { return binarySearch(arr, val, start, middleIndex - 1); } else { return binarySearch(arr, val, middleIndex + 1, end); } } Make sure to include the return statement in the recursive calls to binarySearch to fix the issue.

found a bug in Absolute Beginner’s Guide to Algorithms

kirupa December 15, 2023, 3:57am 2

Wow! You are absolutely right. Thanks for flagging this. I’ve documented it in the errata thread and have also flagged it for correction in future printings.

Topic		Replies	Views
Errata: Data Structures and Algorithms Book! programming	13	1600	March 13, 2025
Why does this binary search return -1 for values that are clearly in the array? web dev	3	50	April 6, 2026
Why does this binary search get stuck near the end? web dev	3	44	April 7, 2026
Why does this binary search return the wrong insertion index for some targets? web dev	3	53	April 5, 2026
Why does this binary search return the wrong insertion index for some targets? web dev	1	30	April 3, 2026

found a bug in Absolute Beginner’s Guide to Algorithms

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found a bug in Absolute Beginner’s Guide to Algorithms

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