Software Engineer · Phone Screen · Coding

Google — Software Engineer ✅ Passed

Level: Unknown Level

Round: Phone Screen · Type: Coding · Difficulty: 7/10 · Duration: 60 min · Interviewer: Unfriendly

Topics: System Design, Data Structures, Algorithms

Location: Mountain View, CA

Interview date: 2026-01-15

Summary

I was asked to implement a complete wait list system.

Details

The coding question I received was to write a complete wait list system with the following requirements:

• Ability to add or remove users from the waitlist
• Ability to view the current queue
• Ability to view the top or bottom k elements in the queue

My approach:

1. I started by discussing the data structures that could be used to implement the wait list, such as a queue or a linked list.
2. I considered the time complexity of each operation (add, remove, view queue, view top/bottom k) for each data structure.
3. I chose to implement the wait list using a priority queue to efficiently support viewing the top/bottom k elements.
4. I implemented the add and remove operations, ensuring that they maintain the priority queue's ordering.
5. I implemented the view queue operation by iterating through the priority queue.
6. I implemented the view top/bottom k elements operation using a min-heap or max-heap, depending on whether I wanted the top or bottom elements.

Key insights:

• The choice of data structure is crucial for the performance of the wait list system.
• Using a priority queue allows for efficient retrieval of the top/bottom k elements.
• The implementation should handle edge cases such as an empty wait list or invalid input.