Cracking the DoorDash Software Engineer Interview: Designing a URL Shortener & More!

Software Engineering
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doordash | 软件工程师 | Interview Experience

Interview Date: Not specified
Result: Rejected
Difficulty: Not specified

Interview Process

  • Tech Screen (10/17): Coding challenge on HackerRank. The candidate was required to write test cases and manage time effectively.

    • Question: Leetcode-style problem.

  • System Design (10/27): Designed a URL Shortener on a HackerRank whiteboard.

    • Considerations:
      1. How to calculate system availability.
      2. Avoiding single-point failure when using a global counter.
      3. Handling 1 million TPS read requests after a write.
      4. Implementing internationalization for access to short URLs created in different regions.

  • Behavioral Questions:

    • Interviewer: Hiring Manager
    • Questions:
      • Why DoorDash?
      • How to handle feedback and improve?
      • Conflict resolution strategies.

  • Debugging (10/28): Debugging a problem related to a Dasher Picker on HackerRank.

    • Task:
      1. Implement addDasher to add a dasher to a map.
      2. Implement pickDasher to randomly select a dasher and adjust the map accordingly.
      3. Discuss optimizations, thread safety, and handling service restarts.

  • Code Craft: Implemented a Bootstrap API on HackerRank.

    • Considerations:
      • Exception handling, multi-threading, retry logic, and timeout management.

Technical Questions

  1. Design URL Shortener: System Design, Availability, Distributed Systems, Internationalization, Caching
  2. Dasher Picker: Data Structure, Random Selection, Thread Safety, Persistence

Tips & Insights

  • Be prepared to write test cases during coding challenges.
  • Understand system design principles, especially around availability and scaling.
  • Practice behavioral questions to articulate experiences effectively.