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Meta·Machine Learning Engineer·Technical Phone Screen·Intermediate

Intermediate
Apr 2026

Summary

Quick Meta ML engineer interview with a single coding-style question. Nothing wild, but it was a bit of a curveball given the role.

Questions Asked (1)

Q1

Given two words, write a function to determine whether they are sorted in lexicographic order.

Algorithms & Data Structures
Author's notes

Felt weirdly simple for an ML role.

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AI HintsAI Generated

Suggested Approach

Clarify the definition of lexicographic order, including case sensitivity and character encoding, then implement a character-by-character comparison that returns true if the first word comes before the second. Handle edge cases such as equal words, empty strings, and different lengths.

Pro tip: Mention that lexicographic order depends on the underlying character encoding (e.g., ASCII vs Unicode) and that in production code you should use built-in string comparison methods for correctness and performance.

1. Clarify requirements

Ask whether the comparison is case-sensitive, which character encoding to assume, and whether equal words are considered sorted.

2. Define lexicographic order

Explain that lexicographic order compares characters by their code points, proceeding from left to right until a difference is found.

3. Design the algorithm

Iterate over the minimum length of the two words, comparing characters at each index; if a difference is found, return whether the first character is less than the second.

4. Handle edge cases

If all compared characters are equal, the shorter word is considered smaller; if lengths are equal, the words are equal and sorted if the problem allows equality.

5. Analyze complexity and test

State that the time complexity is O(min(n, m)) and space is O(1), then walk through test cases like 'apple' vs 'apples', 'Zebra' vs 'apple', and empty strings.

Key Points to Mention

  • Lexicographic order is based on character code points (e.g., ASCII or Unicode).
  • Case sensitivity affects comparison (e.g., 'Z' < 'a' in ASCII).
  • The algorithm compares characters sequentially until a mismatch or end of a string.
  • If one string is a prefix of the other, the shorter string is considered smaller.
  • Time complexity is O(min(n, m)) and space complexity is O(1).
  • In practice, use built-in string comparison methods for reliability and efficiency.

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