Meta·Software Engineer·Onsite - Coding / Algorithms·Intermediate

Intermediate

Jun 2026

Summary

Meta SWE coding round with a string manipulation problem that looks straightforward but has enough edge cases to trip you up if you're not careful about the minimality constraint.

Questions Asked (1)

Given an array of words, generate the shortest unique abbreviation for each word using the format: first letter + count of omitted middle characters + last letter. If words share the same abbreviation, extend the prefix until they diverge. If the abbreviation isn't shorter than the original word, just return the word itself.

Algorithms & Data Structures

Author's notes

I got the basic abbreviation logic down pretty fast but the minimality part with colliding groups took me a while to untangle.

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AI HintsAI Generated

Suggested Approach

Start by grouping words by their initial abbreviation (first letter + count + last letter). For groups with conflicts, iteratively extend the prefix (and adjust the count) until each word's abbreviation is unique. Finally, compare each abbreviation's length to the original word and return the shorter one.

Pro tip: Clarify edge cases upfront, such as words of length 2 (where abbreviation equals the word) and empty input. Also, discuss time/space complexity and potential optimizations like using a trie to efficiently find the shortest unique prefix.

1. Understand the problem and edge cases

Restate the abbreviation format and rules. Identify edge cases: words of length ≤2, duplicate words, and cases where abbreviation is not shorter.

2. Generate initial abbreviations

For each word, compute the initial abbreviation: first char + (length-2) + last char. If length ≤2, the abbreviation is the word itself.

3. Resolve conflicts by extending prefixes

Group words by their initial abbreviation. For each group with more than one word, increase the prefix length (and adjust the count) until all abbreviations in the group are unique.

4. Finalize and compare lengths

For each word, compare the length of its unique abbreviation with the original word. Return the abbreviation if shorter, otherwise return the original word.

5. Analyze complexity and optimize

Discuss time and space complexity. Consider optimizations like using a trie to find the shortest unique prefix for each word efficiently.

Key Points to Mention

Handling edge cases: words of length 1 or 2, duplicate words, and empty input.
Efficient conflict resolution: grouping by initial abbreviation and iteratively extending prefixes.
Correctness of abbreviation format: ensuring the count reflects omitted characters after prefix extension.
Time and space complexity analysis: naive approach vs. trie-based optimization.
Comparison with original word length: only return abbreviation if it's strictly shorter.
Potential follow-up: how to handle large datasets or streaming input.

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