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Anthropic·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Jul 2026Remote

Summary

Anthropic software engineer interview with a graph traversal coding problem. Pretty standard on the surface but they pushed hard on the URL normalization angle which I wasn't fully ready for.

Questions Asked (1)

Q1

Write a function that crawls a website starting from a seed URL and returns all unique pages reachable within the same domain, using a provided helper that returns links for any given page.

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

I went with BFS pretty quickly, which felt right.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints, then outline a BFS-based crawler using a queue and a visited set to avoid cycles. Discuss trade-offs like concurrency, politeness, and error handling, and finally write clean, modular code with clear separation of concerns.

Pro tip: Demonstrate production awareness by mentioning robots.txt, rate limiting, and handling redirects/errors, and suggest using a thread pool or async I/O for scalability while respecting the site's load.

1. Clarify Requirements

Ask about domain scope (subdomains?), depth limits, concurrency, politeness, and error handling to ensure alignment with expectations.

2. Choose Algorithm

Select BFS for systematic coverage and shortest-path discovery, using a queue and a visited set to track unique URLs.

3. Design Data Structures

Use a queue for frontier management, a set for visited URLs, and consider a hash set for O(1) lookups; discuss memory implications.

4. Implement Core Logic

Write a function that dequeues a URL, fetches links via the helper, normalizes and filters them to the same domain, and enqueues unvisited ones.

5. Discuss Enhancements

Talk about adding concurrency (thread pool/async), rate limiting, robots.txt compliance, and handling errors/redirects for robustness.

Key Points to Mention

  • BFS vs DFS: BFS ensures shortest path and systematic coverage, but DFS uses less memory; justify choice.
  • Visited set to avoid cycles and duplicate processing, ensuring uniqueness.
  • URL normalization (e.g., resolving relative links, removing fragments) and domain filtering.
  • Concurrency and scalability: using thread pools or async I/O to speed up crawling while managing load.
  • Politeness and ethics: respecting robots.txt, rate limiting, and setting a user-agent.
  • Error handling: dealing with timeouts, HTTP errors, and redirects gracefully.

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