Airtable·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Apr 2026

Summary

Airtable coding interview with a calendar/holiday problem that starts deceptively simple and then pushes you toward optimization. The discussion-heavy format meant I had to talk through trade-offs without running the code, which is its own kind of pressure.

Questions Asked (1)

Given a set of holiday rules (fixed dates, nth-weekday-of-month rules, and weekend observation adjustments), write code to return all actual holidays within a given year or date range. Start with a brute-force day-by-day approach, then optimize it, and walk through the trade-offs.

Algorithms & Data StructuresTechnical Trade-offs

Author's notes

My first pass was fine, loop every day, check it against each rule type, done.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the holiday rules and expected output format, then implement a brute-force day-by-day solution that checks each date against all rules and applies weekend observation adjustments. After verifying correctness, optimize by computing holiday dates directly from rules and using date arithmetic to avoid iterating over every day, discussing trade-offs like code complexity, performance, and maintainability.

Pro tip: Mention that you would write unit tests for edge cases like holidays falling on weekends, leap years, and year boundaries before optimizing, and emphasize that premature optimization can harm readability when the input size is small.

1. Clarify requirements and edge cases

Ask about the exact holiday rules, how weekend observations work (e.g., observed on Monday if Saturday, Friday if Sunday), and whether the output should include observed dates or actual dates. Confirm the input range and expected output format.

2. Design brute-force approach

Iterate through each day in the given year or range, check if it matches any holiday rule (fixed date, nth weekday), and apply weekend observation adjustments. Collect and return the resulting dates.

3. Implement and test brute-force

Write clean code with helper functions for each rule type, and test with known holidays (e.g., New Year's Day, Thanksgiving) and edge cases like leap years and year boundaries.

4. Optimize by direct computation

Replace day-by-day iteration with direct calculation: for fixed dates, use the date; for nth weekday, compute the first occurrence and add weeks; for weekend adjustments, shift by one or two days. Handle collisions (e.g., two holidays observed on same day) if required.

5. Discuss trade-offs

Compare brute-force vs optimized: brute-force is simpler, less error-prone, and sufficient for small ranges; optimized is faster for large ranges but more complex and harder to maintain. Mention that optimization may be unnecessary unless performance is critical.

Key Points to Mention

Handling different rule types: fixed dates, nth weekday of month, and weekend observation adjustments.
Edge cases: leap years, holidays falling on weekends, year boundaries, and multiple holidays on the same day.
Time and space complexity: brute-force O(days * rules) vs optimized O(holidays) or O(rules).
Code organization: using helper functions for rule evaluation and date manipulation.
Testing strategy: unit tests for each rule type and edge cases.
Trade-offs: simplicity vs performance, and when to choose each approach based on input size and requirements.

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