Airbnb·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Jun 2026

Summary

Airbnb software engineer interview with a coding question around text formatting. The problem had enough edge cases to keep you busy, and the greedy approach felt obvious in hindsight but took a minute to land on during the actual session.

Questions Asked (1)

Write a function that takes a list of articles (each article being a string or list of words) and a max line width, then formats them into lines. Rules: no line exceeds the width, words can't be split, no line starts with punctuation, avoid leaving a single word alone on a line when possible, and insert a '----' separator between consecutive articles. Return the full list of lines.

Algorithms & Data StructuresTechnical Trade-offs

Author's notes

The punctuation-leading rule is what bit me first.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and edge cases, then outline a greedy line-filling algorithm that respects all constraints, and finally discuss trade-offs and potential optimizations. Walk through a small example to demonstrate correctness and handle punctuation and single-word lines explicitly.

Pro tip: Explicitly call out the ambiguity in 'avoid leaving a single word alone' and propose a concrete rule (e.g., if the last line has one word, move a word from the previous line if it fits). This shows you think about real-world edge cases and user experience.

1. Clarify requirements and edge cases

Ask about input format (string vs list of words), punctuation definition, and what 'avoid' means (hard constraint or best effort). Confirm separator behavior and empty article handling.

2. Design the algorithm

Propose a greedy approach: iterate through words, adding to current line if it fits and doesn't start with punctuation. When a line is full, check for single-word line and adjust if possible.

3. Handle special constraints

Implement punctuation check: if next word starts with punctuation, force a line break before it. For single-word lines, try pulling a word from the previous line if it fits without violating width.

4. Insert article separators

After formatting each article, append a '----' line before the next article, ensuring no extra separator at the end.

5. Analyze complexity and trade-offs

Discuss time O(n) and space O(n) where n is total words. Mention that greedy is optimal for line count but may not minimize single-word lines; consider dynamic programming if strict optimization needed.

Key Points to Mention

Greedy line filling with lookahead for punctuation and single-word lines
Handling punctuation: treat as part of word but prevent line starting with it
Single-word line avoidance: heuristic to move word from previous line
Separator insertion logic between articles
Edge cases: empty articles, very long words, width smaller than word length
Complexity analysis and potential DP alternative for optimality

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