HubSpot·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Apr 2026

Summary

HubSpot coding screen focused on a hash map design problem around employee management constraints. Pretty straightforward premise but the dual-constraint angle tripped me up a bit on the first pass.

Questions Asked (1)

Implement an 'add employee to a company' operation that validates two rules: no more than 5 employees per position per company, and no employee can hold more than 2 positions at the same company. Process a list of these operations in order and return success or invalid with the specific rule that was violated for each.

Algorithms & Data StructuresSystem Design

Author's notes

My first instinct was to reach for a nested structure and I wasted a couple minutes mentally organizing it before realizing two flat hash maps keyed by (company, position) and (company, employee) respectively would just...

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AI HintsAI Generated

Suggested Approach

Clarify the input format and edge cases, then design a data structure that tracks employee-position assignments and position counts per company. Process operations sequentially, validating each rule before committing changes, and return the appropriate result for each operation.

Pro tip: Demonstrate foresight by discussing how to extend the solution for concurrency or distributed systems, and mention that the order of validation matters for deterministic error reporting.

1. Clarify requirements and assumptions

Ask about input format, whether employee IDs are unique, if positions are company-specific, and what to return for invalid operations. Confirm that operations are processed in order and that each operation is independent.

2. Design data structures

Choose structures to track: (a) count of employees per position per company, and (b) set of positions per employee per company. Consider using nested maps or composite keys for efficient lookups.

3. Define validation logic

For each add operation, check if adding would exceed 5 employees in that position or if the employee already holds 2 positions at that company. Decide the order of checks and how to report the violated rule.

4. Process operations sequentially

Iterate through the list, apply validations, update data structures only on success, and collect results. Ensure that invalid operations do not alter state.

5. Analyze complexity and edge cases

Discuss time and space complexity, and consider edge cases like duplicate operations, invalid company/position, or employees with multiple positions across companies.

Key Points to Mention

Use of hash maps for O(1) average-case lookups to track counts and employee assignments.
Importance of validating both rules before updating state to avoid partial updates.
Handling of edge cases such as adding the same employee to the same position twice.
Time complexity: O(n) for n operations, with O(1) per operation.
Space complexity: O(m) where m is the number of unique (company, position) and (company, employee) pairs.
Potential for concurrency issues if operations are processed in parallel, and how to address them.

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