Software Engineer · Online Assessment · Coding

Instacart — Software Engineer ✅ Passed

Level: Mid-Level

Round: Online Assessment · Type: Coding · Difficulty: 7/10 · Duration: 240 min · Interviewer: Unfriendly

Topics: Data Structures, Algorithms, System Design

Location: San Francisco, CA

Interview date: 2026-01-24

Summary

The Online Assessment consisted of implementing a worker management system with several functionalities.

Round 1: Worker Management - Part 1

Question: Implement add worker with metadata (id, position, salary), register worker time (start/end time based on office presence), and get all in-office times for a worker.

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Round 2: Worker Management - Part 2

Question: Implement topN workers based on total in-office time, and topN for a specific position, still based on total in-office time.

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Round 3: Worker Management - Part 3

Question: Implement promote worker (title and salary change), but only when the worker is out of the office. If in the office, queue the promotion until the next time they leave. Process only the latest promotion in the queue.

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Round 4: Salary Calculation

Question: Calculate a worker's total salary over a given time period.

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Details

The assessment focused on implementing a system to manage worker information and their time in the office. The functionalities included:

• Adding workers with their metadata.
• Registering worker time based on whether they are entering or leaving the office.
• Retrieving all in-office times for a worker.
• Determining the top N workers based on their total in-office time, both overall and for specific positions.
• Promoting workers, with the promotion only taking effect when the worker is out of the office.
• Calculating a worker's total salary for a given period.

Preparation Tips & Key Takeaways

What I Learned

• Pay close attention to unspecified details in problem descriptions, as assumptions may be required.
• Efficient queue management is important when handling delayed operations.

Recommended Preparation

Data Structures and Algorithms

• Practice implementing data structures like queues and hash maps.
• Focus on time complexity optimization for frequently used operations.

System Design

• Consider how to handle concurrent updates to worker information.
• Design for scalability to handle a large number of workers and operations.

Resources I Recommend

• Review common data structure and algorithm implementations.
• Study system design principles for managing concurrent operations.