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Ramp·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Jun 2026Remote

Summary

Frontend coding round at Ramp for a Software Engineer role. They had me build a Tic-Tac-Toe game from scratch in a single screen, which sounds trivial until you're mid-implementation and the interviewer starts tacking on new requirements. State management and testability were clearly the focus, not the visuals.

Questions Asked (5)

Q1

Build a single-screen Tic-Tac-Toe game that handles player turns, detects wins and draws, prevents invalid moves, and is structured to be easy to test.

Technical Trade-offsSystem DesignAlgorithms & Data Structures
Author's notes

I jumped straight into the UI and spent the first few minutes laying out the grid before I'd even thought about how to represent game state.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints, then outline a clean architecture that separates game logic from UI. Emphasize testability by designing pure functions for move validation, win/draw detection, and state updates, and discuss how you would implement the UI with a focus on simplicity and responsiveness.

Pro tip: Demonstrate testability by writing pseudo-tests for core logic before discussing UI, and mention how you'd use dependency injection to mock the UI layer in tests. This shows you prioritize maintainability and quality.

1. Clarify Requirements and Constraints

Ask about expected tech stack, UI framework, and any specific constraints (e.g., single-screen, no external libraries). Confirm the rules: 3x3 grid, two players, win conditions, draw, invalid move handling.

2. Design Core Game Logic

Define a pure function or class that manages the board state, validates moves, updates turns, and checks for win/draw. Ensure it's independent of UI for testability.

3. Plan the UI Layer

Outline a simple single-screen UI (e.g., React component or vanilla JS) that renders the board, handles clicks, and displays game status. Keep it thin, delegating logic to the core.

4. Ensure Testability

Describe how you would write unit tests for the core logic (e.g., Jest) covering valid moves, invalid moves, win detection, and draw. Mention mocking UI interactions if needed.

5. Discuss Trade-offs and Extensions

Talk about trade-offs (e.g., functional vs. OOP, state management) and potential extensions (e.g., AI opponent, undo) while keeping the single-screen constraint.

Key Points to Mention

  • Separation of concerns: game logic vs. UI
  • Pure functions for move validation and win/draw detection
  • Immutable state updates to avoid side effects
  • Unit testing with edge cases (invalid moves, early wins, full board draw)
  • Single-screen constraint and responsive design
  • Trade-offs between different state management approaches (e.g., useState vs. useReducer)

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

Q2

How would you generalize this implementation to support an NxN board instead of a fixed 3x3?

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

This one I actually handled okay.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the current implementation's assumptions and constraints, then propose a generalized design that replaces hardcoded 3x3 logic with parameterized dimensions. Discuss trade-offs between different approaches (e.g., dynamic allocation vs. fixed max size) and highlight how to maintain performance and readability.

Pro tip: Mention that you would first write tests for the generalized version to ensure backward compatibility and catch edge cases like N=1 or N=0. This shows you think about robustness and maintainability, not just the algorithm.

1. Clarify requirements and constraints

Ask about expected N range, memory limits, and whether the board is sparse or dense. This determines the appropriate data structure and algorithm.

2. Identify hardcoded assumptions

Point out specific places where 3 is hardcoded (e.g., loops, array sizes, win conditions) and explain how to replace them with N.

3. Choose a generalized data structure

Propose using a 2D array or list of lists dynamically sized to N, or a 1D array of size N*N for cache efficiency. Discuss trade-offs.

4. Adapt algorithms and win conditions

Explain how to generalize win-checking (e.g., check rows, columns, diagonals of length N) and any other logic like move validation.

5. Address performance and edge cases

Discuss time/space complexity changes, potential optimizations (e.g., early termination), and handle edge cases like N=1 or N=0.

Key Points to Mention

  • Parameterize board size instead of hardcoding 3
  • Use dynamic memory allocation or resizable containers
  • Generalize win conditions to check N consecutive marks
  • Consider time and space complexity for large N
  • Maintain backward compatibility with existing 3x3 logic
  • Write unit tests for various N values to ensure correctness

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

Q3

How would you add an AI opponent to this game?

Algorithms & Data StructuresTechnical Trade-offs
Author's notes

Blanked for a second.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the game's mechanics and constraints, then propose a layered AI architecture that balances algorithmic sophistication with practical trade-offs. Focus on how you would iterate from a simple baseline to more advanced techniques, justifying each choice based on player experience and engineering effort.

Pro tip: Emphasize that the best AI opponent is one that is fun and beatable, not necessarily the most optimal; discuss how you would tune difficulty and avoid frustrating players. Also, mention that you would instrument the AI to collect data for future improvements.

1. Clarify game rules and constraints

Ask questions to understand the game's state space, action space, win conditions, and performance requirements (e.g., real-time vs. turn-based). This ensures your AI design fits the context.

2. Choose an AI approach

Select an algorithm based on complexity: for simple games, use rule-based or minimax; for complex ones, consider Monte Carlo Tree Search or reinforcement learning. Justify with trade-offs like development time, computational cost, and adaptability.

3. Design the AI architecture

Outline components: state evaluation, decision-making, and difficulty adjustment. Explain how the AI will interface with the game engine and handle real-time constraints.

4. Implement and iterate

Start with a simple baseline (e.g., random or greedy) and incrementally improve. Use profiling and testing to ensure performance and correctness.

5. Tune for player experience

Adjust difficulty via parameters (e.g., search depth, randomness) and gather feedback to make the AI engaging. Consider adding human-like imperfections.

Key Points to Mention

  • Game complexity analysis (state space, branching factor)
  • Algorithm choices: minimax, alpha-beta pruning, MCTS, reinforcement learning
  • Trade-offs: optimality vs. fun, computational resources, development time
  • Difficulty scaling and dynamic adjustment
  • Integration with existing game loop and performance optimization
  • Testing and evaluation metrics (win rate, player satisfaction)

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

Q4

How would you persist match history across sessions?

System DesignData Modeling
Author's notes

Talked through localStorage for a lightweight client-side approach versus a backend with a simple REST endpoint.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the requirements: what 'match history' means in this context (e.g., game matches, user matches, or transaction matches), expected read/write patterns, and scale. Then propose a data model and storage solution (e.g., relational DB with proper indexing, or NoSQL for flexibility) that ensures durability, efficient retrieval, and scalability. Finally, discuss trade-offs and how you would handle edge cases like data consistency and archival.

Pro tip: Demonstrate awareness of Ramp's domain by relating 'match history' to financial transactions or user interactions, and emphasize the importance of auditability and compliance in persistence design.

1. Clarify Requirements

Ask questions to understand what 'match history' entails, the expected volume, read/write ratio, and any latency or consistency requirements.

2. Design Data Model

Propose a schema that captures the necessary entities and relationships, considering normalization vs. denormalization based on access patterns.

3. Choose Storage Technology

Select an appropriate database (e.g., PostgreSQL, DynamoDB) based on requirements, and explain how it supports persistence across sessions.

4. Address Scalability and Performance

Discuss indexing, partitioning, caching, and read replicas to ensure efficient retrieval and handle growth.

5. Handle Edge Cases and Trade-offs

Cover data consistency, backup/recovery, archival, and trade-offs between different approaches.

Key Points to Mention

  • Data modeling: entities, relationships, and schema design
  • Database selection: SQL vs. NoSQL, and why
  • Indexing strategies for efficient querying
  • Scalability: partitioning, sharding, and read replicas
  • Data consistency and transaction guarantees
  • Backup, recovery, and archival policies

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

Q5

How would you prevent unnecessary UI re-renders as the game state updates?

Technical Trade-offsSystem Design
Author's notes

Short answer: memoization and keeping state granular so only the changed cell triggers a re-render.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the game's rendering architecture and the frequency of state updates, then discuss strategies to minimize re-renders such as component memoization, state colocation, and selective subscriptions. Emphasize trade-offs between performance and code complexity, and how you would measure and validate improvements.

Pro tip: Mention that you'd profile first to identify actual bottlenecks rather than prematurely optimizing, and that you'd consider using React DevTools or similar tools to track re-renders.

1. Understand the rendering pipeline

Explain how the game state updates flow through the UI and which components re-render on each update. Identify the root cause of unnecessary re-renders.

2. Apply component-level optimizations

Use techniques like React.memo, useMemo, and useCallback to prevent re-renders when props haven't changed. Split components to isolate state updates.

3. Optimize state management

Colocate state to the nearest common ancestor, use selective subscriptions (e.g., with Redux or Context), and consider external state management like Zustand or Recoil for fine-grained updates.

4. Leverage advanced patterns

For high-frequency updates, consider using requestAnimationFrame, throttling, or debouncing. Explore virtual DOM alternatives like direct DOM manipulation for critical parts.

5. Measure and iterate

Profile the application to identify remaining bottlenecks, measure the impact of changes, and ensure that optimizations don't harm maintainability.

Key Points to Mention

  • React.memo, useMemo, useCallback for preventing unnecessary re-renders
  • State colocation and lifting state up appropriately
  • Selective subscriptions with state management libraries (e.g., Redux with shallowEqual, Zustand)
  • Component splitting and composition to isolate updates
  • Profiling tools (React DevTools, why-did-you-render) to identify bottlenecks
  • Trade-offs between performance optimizations and code complexity/maintainability

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