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Hudson River Trading·Software Engineer·Online Assessment (OA)·Intermediate

Intermediate
May 2026

Summary

HRT software engineer interview, looked like a coding assessment focused on array and string fundamentals. The edge case stuff was more systematic than I expected, less about solving the problem and more about whether you'd thought through the weird inputs before writing a single line.

Questions Asked (1)

Q1

For a typical easy-to-medium array or string problem, what edge cases would you test, and how do you quickly turn those into concrete test inputs and expected outputs during a timed assessment?

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

This tripped me up more than it should have.

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AI HintsAI Generated

Suggested Approach

Start by categorizing edge cases into input extremes, structural properties, and problem-specific constraints. Then, for each category, quickly derive a minimal test input and expected output, focusing on cases that could break your algorithm. Emphasize that you prioritize edge cases based on likelihood and impact, and that you often write these tests before coding to guide your solution.

Pro tip: In a timed assessment, don't just list edge cases—immediately write them as assertions or comments in your code. This shows systematic thinking and helps you catch bugs early, especially when time is tight.

1. Categorize Edge Cases

Group edge cases into input size (empty, single element, large), input values (duplicates, negatives, zeros, special characters), and structural properties (sorted, reverse sorted, all same).

2. Prioritize by Likelihood and Impact

Focus on cases most likely to occur given the problem constraints and those that would cause incorrect results or crashes if unhandled.

3. Generate Concrete Test Inputs

For each prioritized edge case, quickly write a minimal input that triggers it, ensuring it's small enough to manually compute the expected output.

4. Compute Expected Outputs

Manually derive the correct output for each test input, using the problem statement and your understanding of the algorithm.

5. Integrate Tests into Code

Embed these tests as assertions or comments in your solution to validate your algorithm as you code, and mention them in your final explanation.

Key Points to Mention

  • Empty input (empty array/string) and single-element input
  • Arrays with all identical elements or strings with repeated characters
  • Inputs with negative numbers, zeros, or maximum/minimum values
  • Already sorted or reverse-sorted inputs for problems involving order
  • Boundary conditions like maximum length or integer overflow
  • Problem-specific cases such as palindromes, anagrams, or cyclic dependencies

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