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Meta·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Apr 2026

Summary

Meta SWE coding round, basically just the classic array problem. Nothing fancy, nothing surprising.

Questions Asked (1)

Q1

Given an array of integers, return a new array where each element is the product of all other elements in the original array, without using division.

Algorithms & Data Structures
Author's notes

Pretty standard problem if you've seen it before.

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AI HintsAI Generated

Suggested Approach

Clarify the problem constraints (e.g., array size, element types, handling zeros) and then propose a solution using prefix and suffix products. Explain that you can compute prefix products in one pass and suffix products in another, then multiply them to get the result without division. Analyze time and space complexity, aiming for O(n) time and O(1) extra space (excluding output array).

Pro tip: Mention that this approach handles zeros gracefully, unlike division-based solutions, and discuss potential optimizations like using the output array to store prefix products and then computing suffix products on the fly to achieve O(1) extra space.

1. Clarify requirements and edge cases

Ask about input size, element ranges, and whether zeros are allowed. Discuss how zeros affect the result (e.g., if more than one zero, all products are zero; if exactly one zero, only that position gets the product of others).

2. Propose a division-free approach

Explain that you'll use prefix and suffix products. Compute an array where each element is the product of all elements to its left, then multiply by the product of all elements to its right.

3. Detail the algorithm

Describe two passes: first, compute prefix products and store in the output array; second, traverse from right to left, maintaining a running suffix product and multiplying it with the corresponding prefix product.

4. Analyze complexity and optimize

State that time complexity is O(n) and space complexity is O(1) extra space (output array not counted). Mention that this avoids division and handles zeros correctly.

5. Test with examples

Walk through a simple example (e.g., [1,2,3,4]) and an edge case with zeros (e.g., [1,0,3,4]) to verify correctness.

Key Points to Mention

  • Prefix and suffix product technique
  • Handling zeros without division
  • Time complexity O(n) and space complexity O(1) extra space
  • Edge cases: empty array, single element, multiple zeros
  • Avoiding division as per problem constraint
  • In-place computation using the output array

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