Meta·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Jun 2026

Summary

Meta data engineer interview with a coding question around array manipulation. Pretty standard algorithmic problem but worth knowing cold if you're prepping for this role.

Questions Asked (1)

Given a sorted array of integers, return a new sorted array of the squares of each element.

Algorithms & Data Structures

Author's notes

The naive solution is just square everything and sort again, which works but they clearly wanted better.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem and edge cases, then propose a brute-force solution and analyze its complexity. Follow up with an optimal two-pointer approach that leverages the sorted order to achieve O(n) time and O(n) space, and walk through an example to demonstrate correctness.

Pro tip: Explicitly mention that the two-pointer technique works because the largest squares come from the extremes of the sorted array, and offer to code it with clear variable names and comments to show production-quality coding.

1. Clarify and confirm

Ask about input size, duplicates, negative numbers, and whether the output should be a new array. Confirm the expected time/space complexity.

2. Discuss brute force

Mention the naive approach: square each element and sort, which takes O(n log n) time. Acknowledge it's simple but not optimal.

3. Propose optimal two-pointer

Explain that since the array is sorted, the largest square is at either end. Use two pointers starting at both ends, compare absolute values, and fill the result array from the end to the beginning.

4. Walk through an example

Trace the algorithm on a sample array like [-4, -1, 0, 3, 10] to show how pointers move and the result is built.

5. Analyze complexity and edge cases

State that the optimal solution runs in O(n) time and O(n) space. Mention edge cases: empty array, single element, all negatives, all positives, and zeros.

Key Points to Mention

The array is sorted, so the largest squares are at the extremes.
Two-pointer technique from both ends to achieve O(n) time.
Filling the result array from the end to avoid shifting elements.
Comparison based on absolute values (or squares) of the elements.
Handling negative numbers correctly since squaring makes them positive.
Space complexity: O(n) for the output array, which is necessary.

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