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Rokt·Backend Engineer·Technical Phone Screen·Intermediate

IntermediateRejected
May 2026

Summary

Interviewed for a backend role at Rokt. The coding portion was a binary search problem, which I knocked out quickly, but I left with a nagging feeling my background wasn't quite what they were looking for.

Questions Asked (1)

Q1

Implement a solution to a binary search problem.

Algorithms & Data Structures
Author's notes

Solved it fast, no issues.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem requirements and edge cases, then explain the binary search algorithm step-by-step, and finally implement it with clean code while analyzing time and space complexity. Emphasize the importance of correct boundary conditions and avoiding infinite loops.

Pro tip: Demonstrate maturity by discussing how binary search can be adapted to variations like finding the first/last occurrence or searching in rotated arrays, and mention potential pitfalls like integer overflow in midpoint calculation.

1. Clarify the problem

Ask questions to understand the input array (sorted? duplicates?), target value, and expected return (index or boolean). Confirm edge cases like empty array or target not present.

2. Explain the algorithm

Describe binary search: maintain low and high pointers, compute mid, compare with target, and adjust pointers accordingly. Mention the invariant that the target is within the search range if present.

3. Implement the solution

Write clean code with proper variable names and comments. Use low <= high loop condition and update mid as low + (high - low) / 2 to avoid overflow.

4. Test with examples

Walk through a few test cases including edge cases (empty array, single element, target at boundaries, duplicates) to verify correctness.

5. Analyze complexity

State that time complexity is O(log n) and space complexity is O(1) for iterative approach. Mention recursive alternative and its space cost.

Key Points to Mention

  • Binary search requires a sorted array; if not, sorting first would add O(n log n) time.
  • Use low + (high - low) / 2 to prevent integer overflow in languages like Java/C++.
  • Loop condition should be low <= high to handle single-element arrays correctly.
  • Return -1 or appropriate value when target is not found.
  • Discuss variations: finding first/last occurrence, searching in rotated sorted array, or using binary search on answer space.
  • Mention that binary search can be implemented iteratively or recursively, with trade-offs in space.

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