HubSpot Coding Interview Questions
25 HubSpot 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 HubSpot interviewer values, and a FAQ section.
Showing 9 problems of 25
- #4hardoccasionally asked
4. Median of Two Sorted Arrays
HubSpot includes Median of Two Sorted Arrays to assess whether candidates can binary search on a partition index rather than on array values — a conceptual leap that separates strong algorithmic thinkers from those who rely on rote solutions.
- #9easyoccasionally asked
9. Palindrome Number
HubSpot asks Palindrome Number to see whether candidates look for math-based solutions before reaching for string conversion — a habit that signals strong algorithmic instincts beyond language-specific shortcuts.
- #23hardoccasionally asked
23. Merge K Sorted Lists
HubSpot asks Merge K Sorted Lists to see whether you can reason about multi-source merging with a priority queue — a design pattern central to their event-stream aggregation where k data sources need to be merged in order for the activity feed.
- #42hardoccasionally asked
42. Trapping Rain Water
HubSpot asks Trapping Rain Water to evaluate your ability to reason about bounded quantities — how much water a cell can hold is determined by the minimum of the tallest bars on its left and right — a constraint-propagation mindset they value in their data pipeline engineers.
- #127hardoccasionally asked
127. Word Ladder
HubSpot asks Word Ladder to test BFS on an implicit graph where nodes are words and edges are single-character transformations — a pattern that generalizes to shortest-path problems across their CRM entity relationship graph.
- #139mediumoccasionally asked
139. Word Break
HubSpot uses Word Break to test bottom-up dynamic programming and substring reachability — reasoning patterns that map directly to parsing HubSpot's expression language and evaluating segmented workflow conditions.
- #207mediumoccasionally asked
207. Course Schedule
HubSpot asks Course Schedule to assess cycle detection in directed graphs — a pattern that arises in their workflow automation engine where circular dependency detection between triggers and actions is a critical correctness guarantee.
- #297hardoccasionally asked
297. Serialize and Deserialize Binary Tree
HubSpot asks Serialize and Deserialize Binary Tree to test OOP design instincts alongside algorithmic thinking — you must design a codec that faithfully round-trips any tree structure, mirroring how their backend engineers design data serialization schemas for tree-structured CRM objects.
- #322mediumoccasionally asked
322. Coin Change
HubSpot uses Coin Change to probe unbounded knapsack / bottom-up DP thinking — the same pattern that underlies their pricing-plan composer and subscription credit allocation logic, where achieving an exact amount from discrete denominations matters.
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