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Meta·Software Engineer·Online Assessment (OA)·Senior

Senior
Apr 2026

Summary

Meta coding round for a software engineer role, done inside a large existing codebase you had to read and extend rather than start from scratch. The core problem was a card game with a specific scoring mechanic and you had to build out a strategy layer on top of it. Definitely a different format than the usual blank-slate leetcode setup.

Questions Asked (3)

Q1

Given a card game where sets of 3 cards summing to 15 score points and cards are continuously replenished from a deck, implement a strategy that maximizes total score across a full game. You're working inside a large pre-existing codebase.

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

The setup itself wasn't too bad to understand but the codebase context made everything slower.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem constraints and game mechanics, then propose a greedy strategy with a priority queue to always pick the highest-scoring set, and discuss how to integrate it into the existing codebase with minimal disruption. Finally, analyze trade-offs and potential optimizations.

Pro tip: Demonstrate awareness of the existing codebase by suggesting to first locate and understand the current game loop and card representation before designing the strategy. This shows you value maintainability and integration over just algorithmic prowess.

1. Clarify Requirements and Constraints

Ask questions to understand the game rules, scoring, deck size, card values, and replenishment mechanics. Confirm whether the goal is to maximize score for a single player or if there are opponents.

2. Design the Algorithm

Propose a greedy approach: at each turn, find all valid sets of 3 cards summing to 15, choose the one with highest immediate score (if scores vary), and remove those cards. Use a priority queue or sorted structure to efficiently retrieve the best set.

3. Integrate with Existing Codebase

Identify where the game loop and card management reside. Suggest adding a new strategy module that adheres to existing interfaces, and use dependency injection or strategy pattern to plug it in without modifying core logic.

4. Analyze Trade-offs and Optimizations

Discuss time/space complexity, potential for lookahead or dynamic programming if greedy is suboptimal, and how to handle ties or edge cases. Mention testing and validation against existing tests.

Key Points to Mention

  • Greedy algorithm with priority queue for efficient set selection
  • Time complexity: O(n log n) per turn if using heap, overall O(n^2 log n) for n turns
  • Strategy pattern or dependency injection for seamless integration
  • Potential need for lookahead or DP if greedy fails to maximize total score
  • Handling card replenishment and ensuring no duplicate cards are used
  • Testing strategy: unit tests for set finding and integration tests for game simulation

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

Q2

When multiple valid disjoint sets of 3 cards are all playable at the same time, how do you decide which one to play first, and does the order even matter?

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

This is where I stumbled a bit.

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AI HintsAI Generated

Suggested Approach

Clarify the problem context and constraints first, then analyze whether the order of playing disjoint sets affects the final outcome or intermediate states. Discuss trade-offs between different strategies (e.g., greedy vs. optimal) and justify your choice based on the problem's requirements.

Pro tip: In many cases, the order doesn't matter if the sets are truly disjoint and the goal is just to play all valid sets. However, if there are side effects or resource constraints, order can matter. Always ask clarifying questions to understand the problem fully.

1. Clarify the problem

Ask questions to understand the rules: What defines a valid set? Are there constraints like limited moves or time? What is the objective (e.g., maximize score, minimize moves)?

2. Analyze independence

Determine if the sets are truly independent. If playing one set affects the availability or validity of another, order matters. Otherwise, it may not.

3. Consider side effects

Identify any side effects of playing a set, such as changing the game state, consuming resources, or triggering events. These can make order important.

4. Evaluate strategies

If order matters, discuss possible strategies (e.g., greedy, heuristic, exhaustive search) and their trade-offs in terms of time complexity and optimality.

5. Conclude with recommendation

Based on the analysis, recommend whether order matters and, if so, which strategy to use. Justify with reasoning about correctness and efficiency.

Key Points to Mention

  • Definition of disjoint sets and validity conditions
  • Independence of sets and potential interactions
  • Side effects or state changes from playing a set
  • Trade-offs between greedy and optimal strategies
  • Time and space complexity of different approaches
  • Importance of clarifying questions in ambiguous problems

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

Q3

How deep a search tree can you realistically afford here, and what's your justification for the cutoff?

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

Blanked for a second on the branching factor math.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem constraints (input size, time/memory limits, branching factor) and then derive a depth bound using complexity analysis. Justify the cutoff by balancing worst-case resource usage against expected solution quality, and mention pruning or iterative deepening as ways to extend effective depth.

Pro tip: Quantify the trade-off with concrete numbers (e.g., 'At depth 10 with branching factor 3, we'd explore ~59k nodes, which fits in 100ms') to show you think in terms of real system limits, not just theory.

1. Clarify constraints and assumptions

Ask about input size, time/memory limits, branching factor, and whether the search is exhaustive or heuristic. State any assumptions you make.

2. Model the search cost

Express the number of nodes as a function of depth (e.g., O(b^d)) and relate it to the available time and memory budget.

3. Derive a depth bound

Solve for the maximum depth that fits within the budget, considering worst-case and average-case scenarios.

4. Justify the cutoff with trade-offs

Explain why that depth is acceptable: it balances solution quality, latency, and resource usage. Mention alternatives like pruning or iterative deepening.

5. Validate and iterate

Propose empirical testing or profiling to confirm the cutoff, and describe how you'd adjust it if constraints change.

Key Points to Mention

  • Time and space complexity of the search (e.g., O(b^d) nodes, O(d) or O(b^d) memory)
  • Branching factor and its impact on exponential growth
  • Pruning techniques (alpha-beta, branch-and-bound) that reduce effective depth
  • Iterative deepening to manage memory while allowing deeper search
  • Real-world constraints: latency SLAs, memory limits, and hardware
  • Heuristics or evaluation functions that guide search and improve quality at shallower depths

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