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Glean·Machine Learning Engineer·Take-home Assignment·Senior

SeniorPrefer not to say
May 2026

Summary

Glean gave me a 75-minute AI-assisted coding assignment to build a Wikipedia crawler with some specific prioritization logic. The tool choice felt off and I spent most of the session trying to decipher code I didn't fully trust.

Questions Asked (1)

Q1

Build a Wikipedia crawler that prioritizes pages whose title starts with a letter not yet visited. Once all 26 letters are covered, fall back to random crawling. Must respect a rate limit. You can use AI coding tools.

Algorithms & Data StructuresSystem DesignTechnical Trade-offs
Author's notes

The logic itself isn't that bad once you map it out.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints, then outline a modular design with a priority queue for letter coverage and a rate limiter. Discuss trade-offs between strict letter-first and random fallback, and how AI tools can accelerate implementation while ensuring correctness.

Pro tip: Mention that you would use AI tools to generate boilerplate and tests, but manually verify the priority logic and rate limiting to avoid subtle bugs. Also, discuss how to handle edge cases like pages with non-alphabetic titles.

1. Clarify Requirements

Ask about rate limit specifics (e.g., requests per second), definition of 'title starts with a letter' (case sensitivity, non-ASCII), and whether the crawler should avoid revisiting pages.

2. Design Data Structures

Use a set to track visited letters and a priority queue or separate queues for each letter to prioritize unvisited letters. Maintain a visited set for URLs to avoid duplicates.

3. Implement Rate Limiting

Use a token bucket or leaky bucket algorithm to enforce the rate limit, ensuring requests are spaced appropriately. Consider using a library or simple sleep-based approach.

4. Crawling Logic

While unvisited letters exist, prioritize fetching pages whose titles start with those letters. Once all letters are visited, switch to random crawling from a frontier of discovered links.

5. Leverage AI Tools

Use AI to generate initial code, unit tests, and documentation, but review and refine the priority logic and rate limiter manually to ensure correctness and efficiency.

Key Points to Mention

  • Priority queue or multiple queues for letter-based prioritization
  • Rate limiting algorithms (token bucket, leaky bucket) and their trade-offs
  • Handling edge cases: non-alphabetic titles, case sensitivity, Unicode
  • Avoiding duplicate visits with a visited set and URL normalization
  • Fallback to random crawling after all letters covered
  • Using AI tools for boilerplate and testing, but verifying critical logic

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