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

Intermediate
Jun 2026Remote

Summary

Meta virtual onsite coding round, got a stock trading problem that was close to a well-known leetcode problem but with a twist thrown in. Nothing too crazy but the variation kept me on my toes.

Questions Asked (1)

Q1

Given an array of stock prices where each index represents a day, find the maximum profit you can make by buying and selling once. The problem included a variation from the standard version.

Algorithms & Data Structures
Author's notes

Knew the base problem cold so I jumped straight to the single-pass solution with a running minimum.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem and the variation, then explain the standard one-pass solution for the basic version. Adapt your approach to the variation by identifying how it changes the problem constraints and modifying the algorithm accordingly.

Pro tip: Always discuss time and space complexity trade-offs, and mention edge cases like decreasing prices or single-day arrays. This shows thoroughness and practical engineering thinking.

1. Clarify the problem and variation

Ask questions to understand the exact variation (e.g., multiple transactions, cooldown, transaction fee) and confirm input/output expectations.

2. Explain the standard solution

Describe the one-pass approach for the basic 'buy and sell once' problem, tracking minimum price and maximum profit.

3. Adapt to the variation

Modify the algorithm based on the variation, explaining how the change affects the logic and complexity.

4. Analyze complexity and edge cases

State time and space complexity, and discuss edge cases such as empty array, single element, or strictly decreasing prices.

5. Test with examples

Walk through a small example to validate the solution and demonstrate correctness.

Key Points to Mention

  • Time complexity: O(n) for one-pass solutions
  • Space complexity: O(1) for basic version
  • Handling edge cases: empty array, single day, decreasing prices
  • The importance of clarifying the variation before coding
  • Trade-offs between different approaches (e.g., brute force vs. optimized)
  • Potential follow-up variations (e.g., multiple transactions, cooldown)

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