Google·Software Engineer·Technical Phone Screen
Jun 2026
Google SWE interview centered entirely on a trie-based autocomplete design problem. It went deeper than I expected, covering data structure choices, complexity analysis, and a full dry-run trace through several operations.
- Design and implement an autocomplete service using a prefix tree. Support insert(word, weight), update(word, newWeight), delete(word), and topK(prefix, k) returning the k highest-weight words under that prefix, with lexicographic tiebreaking. Walk through the data structures you'd store at each node to make topK efficient, analyze time and space complexity per operation, and discuss trade-offs between caching sorted results at nodes versus computing on demand.
“This was the whole interview basically.” The rest of the author's notes on Software Engineer interview at Google, Technical Phone Screen round, covers how they worked through the question, what the panel pushed back on, and what they would do differently.
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