NURO·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

Jun 2026

Summary

Nuro SWE interview with a systems-flavored coding problem. Not your typical leetcode grind, which threw me off a bit.

Questions Asked (1)

You have a function that returns a car's current position. Implement a new function that can return the car's position at any given timestamp from the past 10 seconds.

Algorithms & Data StructuresSystem DesignTechnical Trade-offs

Author's notes

My first instinct was a circular buffer and I went with it, which I think was right, but I spent too long explaining the data structure before actually coding anything.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the requirements: the function returns the car's current position, and we need to query historical positions up to 10 seconds ago. Propose a data structure like a circular buffer or deque to store timestamped positions, and discuss trade-offs between memory usage, accuracy, and query performance.

Pro tip: Mention that you would use a monotonic clock (e.g., System.nanoTime()) to avoid issues with system clock adjustments, and consider interpolation for timestamps not exactly stored.

1. Clarify Requirements

Ask about the expected query rate, precision of timestamps, memory constraints, and whether interpolation is needed. Confirm the 10-second window and that the function should handle timestamps within that window.

2. Choose Data Structure

Select a circular buffer (ring buffer) or deque to store (timestamp, position) pairs. This provides O(1) insertion and O(log n) or O(n) lookup, with bounded memory.

3. Design Update Mechanism

Modify the existing position-returning function to also record each new position with a timestamp into the buffer, evicting entries older than 10 seconds.

4. Implement Query Function

For a given timestamp, search the buffer (e.g., binary search if sorted) to find the closest recorded position. If exact match not found, return the nearest earlier position or interpolate.

5. Discuss Trade-offs

Compare approaches: fixed-size array vs. dynamic list, exact vs. interpolated results, and memory vs. accuracy. Mention concurrency considerations if the function is called from multiple threads.

Key Points to Mention

Use of a circular buffer or deque to maintain a sliding window of the last 10 seconds.
Timestamping with a monotonic clock to avoid system time changes.
Binary search for efficient lookup if data is sorted by timestamp.
Interpolation (e.g., linear) for timestamps between recorded points.
Memory management: eviction of old data to keep memory bounded.
Thread safety if the function is accessed concurrently.

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