← Bitkernel Interview Insights

Bitkernel·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jul 2026

Summary

Bitkernel software engineer interview with a binary search tracing question. Pretty standard algorithmic stuff but the exact comparison counts tripped me up more than I expected.

Questions Asked (1)

Q1

Given a sorted 10-element array, trace through binary search using floor-based midpoint calculation to find the keys 77, 34, and 99. How many comparisons does each search require, and what is the resulting triple?

Algorithms & Data Structures
Author's notes

I knew binary search cold, or so I thought.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

First, clarify the array contents and the floor-based midpoint formula, then simulate each search step-by-step, counting comparisons until the key is found or the search space is exhausted. Finally, report the comparison counts and the resulting triple in the order of the keys given.

Pro tip: Mention that floor-based midpoint avoids ambiguity and is standard in many implementations; also note that the number of comparisons can vary slightly depending on whether you count the final unsuccessful comparison.

1. Clarify assumptions

Confirm the array elements (e.g., 10, 22, 34, 45, 56, 67, 77, 88, 99, 100) and that midpoint is calculated as floor((low + high) / 2).

2. Trace search for 77

Start with low=0, high=9. Compute mid, compare, and adjust low/high until 77 is found. Count each comparison.

3. Trace search for 34

Repeat the binary search process for key 34, carefully updating low and high based on comparisons, and count comparisons.

4. Trace search for 99

Perform binary search for key 99, noting that it may require more steps if it is near the end of the array. Count comparisons.

5. Compile results

List the number of comparisons for each search in the order 77, 34, 99, and present the resulting triple (e.g., (3, 4, 4)).

Key Points to Mention

  • Binary search requires a sorted array and works by repeatedly dividing the search interval in half.
  • Floor-based midpoint calculation: mid = floor((low + high) / 2).
  • Comparison count includes each element-to-key comparison, including the final successful match.
  • The number of comparisons is at most ceil(log2(n+1)) for a successful search in a sorted array of size n.
  • For unsuccessful searches, the number of comparisons equals the number of steps until low > high.
  • The resulting triple depends on the specific array contents; if the array is not given, state the assumed array.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.