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 8 problems of 25
- #1easyfrequently asked
1. Two Sum
HubSpot uses Two Sum as a warm-up screen to see if you can jump straight from brute force to an O(n) hash-map solution while explaining your reasoning out loud — a habit their Boston engineering culture values deeply.
- #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.
- #20easyfrequently asked
20. Valid Parentheses
HubSpot asks Valid Parentheses to test stack intuition and edge-case discipline — skills that surface constantly when parsing template syntax, email tokens, or workflow expression strings in their CRM platform.
- #21easyfrequently asked
21. Merge Two Sorted Lists
HubSpot asks Merge Two Sorted Lists to evaluate pointer hygiene and recursive vs. iterative trade-offs — skills that translate directly to merging ordered event streams and sorted activity logs in their CRM timeline features.
- #53easyfrequently asked
53. Maximum Subarray
HubSpot asks Maximum Subarray to test Kadane's algorithm — one of the most elegant greedy/DP hybrids in the canon — and to see whether you can clearly articulate why dropping a negative prefix always improves the running sum.
- #70easyfrequently asked
70. Climbing Stairs
HubSpot uses Climbing Stairs as an entry point into dynamic programming thinking — they want to see you recognize overlapping subproblems and memoize rather than recompute, a discipline that directly applies to their complex workflow-evaluation engines.
- #121easyfrequently asked
121. Best Time to Buy and Sell Stock
HubSpot includes this classic sliding-window / greedy problem to test whether you can track a running minimum while computing a maximum difference — a pattern that recurs in revenue-trend analysis across their sales CRM data pipelines.
- #206easyfrequently asked
206. Reverse Linked List
HubSpot includes Reverse Linked List to confirm you can manipulate pointer-based structures precisely — an essential skill for engineers working on their pipeline and activity-feed data models where ordered traversal matters.
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