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Google·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Google frontend engineer interview, got asked a pretty classic JS array manipulation problem. Nothing too wild but it still made me think more than I expected.

Questions Asked (1)

Q1

Given an array of objects, how would you remove duplicate entries?

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

Seemed simple at first and I jumped straight to using a Map keyed by some unique property.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the definition of 'duplicate' (e.g., based on object identity or specific properties) and the desired output (e.g., preserve order, return new array). Then discuss multiple approaches, comparing time/space complexity and trade-offs, and finally recommend the most suitable one for the given context.

Pro tip: Mention that using a hash-based approach is typically O(n) time, but if objects are large or have many properties, consider hashing only a subset of properties or using a custom hash function to improve performance.

1. Clarify requirements

Ask whether duplicates are defined by object identity or by specific properties, and whether the original order should be preserved.

2. Discuss naive approaches

Mention O(n^2) solutions like nested loops with deep equality checks, and their inefficiency for large arrays.

3. Propose efficient solutions

Describe hash-based approaches: using a Set with JSON.stringify for simple cases, or a Map with a custom key derived from selected properties.

4. Analyze trade-offs

Compare time and space complexity, discuss limitations (e.g., JSON.stringify order sensitivity, handling nested objects), and consider edge cases.

5. Recommend and conclude

Choose the best approach based on constraints, and mention potential optimizations or alternative data structures.

Key Points to Mention

  • Definition of duplicate: object identity vs. property-based equality
  • Time and space complexity of different approaches (O(n^2) vs. O(n))
  • Use of hash-based data structures like Set or Map
  • Serialization methods (e.g., JSON.stringify) and their pitfalls
  • Preservation of original order and stability
  • Handling nested objects and custom equality functions

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