Hadn't touched OOP in about a year and the interviewer read the whole thing out loud instead of pasting it, so the first few minutes were rough just trying to hold all the pieces in my head.
Start by clarifying the problem requirements and constraints, then design a clean object-oriented solution using appropriate data structures. Be prepared to extend your design iteratively by discussing trade-offs and adapting to new constraints.
Pro tip: Demonstrate foresight by anticipating follow-up constraints and designing with extensibility in mind, but avoid over-engineering. Communicate your thought process clearly, as Google values problem-solving and collaboration.
Ask questions to understand the problem scope, expected inputs/outputs, and any initial constraints. Confirm assumptions before diving into design.
Outline the main classes, their responsibilities, and interactions. Choose appropriate data structures (e.g., hash maps, trees, graphs) based on operations and complexity.
Discuss time and space complexity, and compare alternative data structures or design patterns. Justify your choices based on the problem context.
For each new constraint, explain how you would modify the design. Focus on maintainability, scalability, and potential refactoring.
Walk through edge cases and test scenarios to ensure correctness. Mention unit testing and how you would verify the solution.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.