Glean Coding Interview Questions
25 Glean coding interview problems with full optimal solutions — 8 easy, 12 medium, 5 hard. Every problem ships with multiple approaches (brute-force first, then the optimal), complexity tables for each, company-specific tips on what an Glean interviewer values, and a FAQ section.
Showing 5 problems of 25
- #3mediumvery frequently asked
3. Longest Substring Without Repeating Characters
Glean asks this to test sliding-window fluency — the same technique used in tokenizing and windowing text streams for indexing, where you need to identify the longest unique n-gram span without repetition.
- #139mediumvery frequently asked
139. Word Break
Glean asks Word Break because query segmentation — splitting a raw search string like 'enterpriseaichat' into 'enterprise ai chat' — is a real pipeline step in their search engine, and the DP solution maps directly to it.
- #146mediumvery frequently asked
146. LRU Cache
Glean uses LRU Cache to test data structure composition — the same hash map + doubly-linked list pattern that sits at the heart of their real-time document caching layer, where recently accessed enterprise content must be served with sub-millisecond latency.
- #208mediumvery frequently asked
208. Implement Trie (Prefix Tree)
Glean is an enterprise search company — Tries are the backbone of autocomplete and prefix-lookup in their search bar. Expect this to come up and expect deep follow-up questions about real-world trie extensions.
- #347mediumvery frequently asked
347. Top K Frequent Elements
Glean loves this problem because top-K selection is literally how search result ranking works — retrieving the K most relevant documents from a frequency-weighted index without sorting all candidates.