← Uber Interview Insights

Uber·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Uber SWE interview with a deceptively simple autocomplete problem. The prompt was basically one line, which meant the real test was how much you could unpack from almost nothing.

Questions Asked (1)

Q1

Given a list of store names, implement an autocomplete function that returns all stores whose names begin with a given input string.

Algorithms & Data StructuresTechnical Trade-offsAdaptability & Ambiguity
Author's notes

The prompt was genuinely short, like one sentence and a list of strings.

Create a free account to read the full note

AI HintsAI Generated

Suggested Approach

Start by clarifying requirements (case sensitivity, result ordering, scale) and then propose a trie-based solution for efficient prefix search. Discuss trade-offs between preprocessing and query time, and mention how to handle large datasets with distributed or cached approaches.

Pro tip: At Uber's scale, autocomplete must handle millions of queries with low latency; mention that you'd precompute top results per prefix and use a distributed cache like Redis to serve them quickly.

1. Clarify Requirements

Ask about input size, expected query volume, case sensitivity, ordering of results, and whether the store list is static or dynamic.

2. Choose Data Structure

Propose a trie (prefix tree) for efficient prefix matching, or a sorted array with binary search if the list is static and memory is a concern.

3. Design Algorithm

Outline insertion and query operations: build the trie by inserting all store names, then traverse to the prefix node and collect all descendant store names.

4. Optimize for Scale

Discuss precomputing top suggestions per prefix, caching frequent queries, and sharding the trie for distributed systems.

5. Analyze Trade-offs

Compare time/space complexity of different approaches and justify your choice based on the clarified requirements.

Key Points to Mention

  • Trie data structure and its O(L) query time where L is prefix length
  • Trade-offs between preprocessing (building trie) and query latency
  • Handling case sensitivity and Unicode normalization
  • Scalability: sharding, caching, and distributed tries for large datasets
  • Dynamic updates: how to handle additions/deletions of store names
  • Ranking results by popularity or relevance, not just alphabetical order

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