Robinhood·Frontend Engineer·Technical Phone Screen·Intermediate

IntermediateRejected

May 2026

Summary

Did a frontend coding round for Robinhood and it didn't go great. The question was a UI build with some state management decisions that I fumbled pretty badly in hindsight.

Questions Asked (1)

Build a 7-day weekly calendar UI where columns represent hourly time slots and rows represent days. Clicking a cell should open a dialog to add an event name.

Technical Trade-offsSystem Design

Author's notes

I went with two separate state objects: a 2D grid and an events list, then derived one from the other.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints, then outline a component-based architecture with a grid layout, state management, and dialog interaction. Discuss trade-offs between CSS Grid and other layout methods, performance optimizations for rendering many cells, and accessibility considerations.

Pro tip: Mention that you would virtualize the calendar grid if the time range is large, but for a 7-day view with hourly slots, it's likely unnecessary; this shows you understand performance without over-engineering.

1. Clarify Requirements

Ask about the time range (e.g., 24 hours or business hours), whether events can span multiple slots, and if there are any constraints like time zones or recurring events.

2. Design Component Structure

Break down the UI into components: CalendarGrid, DayColumn, TimeSlot, and EventDialog. Decide on state management (local state vs. global) and data flow.

3. Choose Layout and Styling

Use CSS Grid for the overall layout, with rows for days and columns for hours (or vice versa). Ensure responsiveness and consider using a library like React Big Calendar for inspiration.

4. Implement Interaction

Handle cell click to open a dialog, manage form input for event name, and update state to reflect the new event. Ensure the dialog is accessible (focus management, keyboard navigation).

5. Discuss Trade-offs and Optimizations

Talk about performance (memoization, virtualization), accessibility (ARIA roles, keyboard support), and potential extensions like drag-and-drop or event editing.

Key Points to Mention

Use CSS Grid for efficient 2D layout and easy responsiveness.
State management: lift state up to a parent component or use context/Redux for scalability.
Accessibility: ensure dialog is keyboard navigable, use ARIA labels for grid cells.
Performance: avoid unnecessary re-renders with React.memo or useMemo for cell components.
Trade-offs: virtual scrolling vs. simple rendering for a fixed 7x24 grid.
Extensibility: design with future features in mind, like event duration or drag-and-drop.

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