Meta·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Jun 2026

Summary

Meta SWE coding question, pretty straightforward array manipulation problem but the setup with two separate arrays tripped me up for a second.

Questions Asked (1)

Given two arrays of departure ticket prices and return ticket prices, find the minimum total cost for a round trip.

Algorithms & Data Structures

Author's notes

Seemed obvious at first, just grab the min from each array and add them.

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AI HintsAI Generated

Suggested Approach

Clarify that the minimum total cost is the sum of the minimum departure price and the minimum return price, as the two legs are independent. Then propose a single-pass solution that tracks the minimum of each array in O(n + m) time and O(1) space. If the problem instead requires pairing specific departure and return tickets, ask for clarification and adapt to a two-pointer or sorting approach.

Pro tip: Always confirm whether the arrays are independent or paired; Meta interviewers often expect you to handle ambiguity and optimize for the common case, but showing you can adapt to constraints demonstrates senior-level thinking.

1. Clarify the problem

Ask whether the departure and return tickets are independent or must be paired, and whether the arrays are sorted or have any constraints. Confirm that the goal is to minimize the sum of one departure and one return price.

2. Identify the optimal substructure

Recognize that if the choices are independent, the minimum total cost is simply the minimum departure price plus the minimum return price. This reduces the problem to finding the minimum in each array.

3. Design an efficient algorithm

Propose a linear scan of each array to find the minimum values, achieving O(n + m) time and O(1) extra space. If the arrays are sorted, mention that the minimums are at the first indices, giving O(1) time.

4. Handle edge cases and alternatives

Discuss edge cases such as empty arrays or negative prices. If the problem requires pairing, outline a two-pointer approach after sorting both arrays, or a brute-force O(n*m) method for small inputs.

5. Analyze complexity and test

State the time and space complexity of your solution. Walk through a small example to verify correctness, and consider writing pseudocode or actual code if requested.

Key Points to Mention

Independence of departure and return choices allows summing individual minimums.
Linear time complexity O(n + m) and constant space O(1) for the independent case.
Edge cases: empty arrays, negative prices, or single-element arrays.
If pairing is required, sorting and two-pointer technique can find the minimum sum pair in O(n log n + m log m).
Clarifying questions are crucial to avoid solving the wrong problem.
Trade-offs between different approaches and their applicability based on constraints.

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