Amazon·Software Engineer·Online Assessment (OA)·Intermediate

IntermediatePending

Sep 2026Remote

Summary

Got an OA from Amazon recently and it was rougher than expected. The coding portion combined BFS, binary search, and some math trick I barely pieced together, plus there was an AI coding section and a work simulation with leadership principles.

Questions Asked (1)

Solve a coding problem requiring BFS traversal, binary search, and a non-obvious mathematical insight to arrive at the solution.

Algorithms & Data Structures

Author's notes

I can handle most mediums on leetcode these days, so I went in feeling okay.

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AI HintsAI Generated

Suggested Approach

First, clarify the problem and constraints, then identify that BFS is needed for level-order traversal or shortest path. Next, recognize where binary search can optimize a search over a sorted or monotonic space. Finally, derive the mathematical insight that simplifies the problem, and combine these techniques into an efficient solution.

Pro tip: At Amazon, interviewers value clear communication and the ability to explain why each technique is chosen. Walk through your reasoning step-by-step, and if you get stuck on the math insight, try small examples to spot a pattern.

1. Understand the problem

Ask clarifying questions to confirm input/output, constraints, and edge cases. Restate the problem in your own words to ensure alignment.

2. Identify BFS and binary search roles

Determine where BFS is needed (e.g., level-order traversal, shortest path) and where binary search can be applied (e.g., searching a sorted array or monotonic predicate).

3. Derive the mathematical insight

Analyze the problem to find a non-obvious mathematical property or formula that reduces complexity. Test with small examples to validate.

4. Design and analyze the algorithm

Combine BFS, binary search, and the insight into a coherent algorithm. Analyze time and space complexity, and discuss trade-offs.

5. Implement and test

Write clean code, then walk through test cases including edge cases. Be prepared to optimize or adjust based on interviewer feedback.

Key Points to Mention

BFS for level-order traversal or shortest path in unweighted graphs
Binary search on a sorted array or monotonic function to achieve O(log n) time
Mathematical insight that simplifies the problem (e.g., parity, modular arithmetic, or invariant)
Time and space complexity analysis of the combined approach
Edge cases such as empty input, single element, or large constraints
Communication of thought process and trade-offs between different approaches

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