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Amazon·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say
Apr 2026

Summary

Amazon SWE interview with a pretty eye-opening final segment: a 20-minute open-ended design question where the interviewer was unusually hands-on with guidance, and then dropped some candid advice during Q&A that I wasn't expecting at all.

Questions Asked (1)

Q1

Design a system for a robot to detect and avoid humans. You can describe the architecture in pseudocode or plain text.

System DesignTechnical Trade-offsAdaptability & Ambiguity
Author's notes

This one surprised me.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and constraints (e.g., robot type, environment, safety guarantees) to show you can handle ambiguity. Then propose a layered architecture with sensing, perception, planning, and control, and discuss trade-offs between different approaches. Finally, walk through a concrete example or pseudocode to demonstrate feasibility.

Pro tip: Emphasize safety-critical design: include redundancy, fail-safes, and real-time constraints, and discuss how you would validate the system through simulation and testing. This shows maturity beyond just algorithmic details.

1. Clarify Requirements

Ask questions to understand the robot's form factor, operating environment, human detection range, safety standards, and performance constraints (e.g., latency, power).

2. High-Level Architecture

Outline the main components: sensors (e.g., LiDAR, cameras, ultrasonic), perception (detection, tracking, prediction), planning (path planning, obstacle avoidance), and control (actuation).

3. Detailed Design & Algorithms

Describe specific techniques for each component, such as YOLO for human detection, Kalman filters for tracking, and potential fields or RRT* for path planning. Mention trade-offs (e.g., accuracy vs. speed).

4. Safety & Redundancy

Explain fail-safes: emergency stop, redundant sensors, watchdog timers, and graceful degradation. Discuss how to ensure real-time performance and safety certification.

5. Validation & Iteration

Propose simulation (e.g., Gazebo, CARLA) and real-world testing, including edge cases (crowded spaces, occlusions). Mention metrics for success (e.g., detection rate, false positives).

Key Points to Mention

  • Sensor fusion (combining LiDAR, cameras, etc.) to improve robustness
  • Real-time constraints and latency requirements for safety
  • Human trajectory prediction to avoid future collisions
  • Trade-offs between reactive (e.g., potential fields) and deliberative (e.g., path planning) approaches
  • Fail-safe mechanisms and redundancy for safety-critical systems
  • Simulation and testing methodologies for validation

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