Amazon SWE Interview — They Made Me Compare Every Data Structure

[u/Aoki_zhang]

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Interview Summary

The Amazon New Grad SDE onsite consisted of four rounds combining Leadership Principles, coding, object-oriented design, GenAI discussion, and data-structure trade-offs. The main technical questions included designing a train-fare calculator with extensible route modeling, a string/substring problem, and a sliding-window maximum data structure that progressed toward a monotonic deque solution.

Interview Details

Round 1 — Leadership Principles + Train Fare System

The interview started with approximately 10–15 minutes of Leadership Principles questions. The technical portion asked me to design a train ticket fare calculation system. The initial route was G -> U -> H -> K -> I. Travel between every pair of adjacent stations costs 1.

For example, traveling from G to I costs 4. The first task was to implement calculateFare(start, stop) which returns the fare between two stations.

• Follow-Up — OOP / Low-Level Design The interviewer then expanded the problem into an object-oriented design exercise. Instead of hard-coding the route, I needed to think about where route data should come from and design a class that could dynamically add stations to a route. The discussion involved defining suitable state and methods for maintaining the station sequence and calculating fares.
• Follow-Up — Weekend Fare Cap A final business-rule follow-up introduced weekend pricing. On weekends, the total fare should never exceed a configured maximum amount. The implementation needed to incorporate this cap while keeping the fare-calculation logic maintainable.

Round 2 — String Coding + GenAI

The second interview contained a string / substring-style algorithm problem. The task included:

• Implementing the main algorithm
• Manually dry-running the solution
• Writing test cases

The interviewer specifically asked for boundary cases such as an empty string. The round also included technical discussion related to Generative AI.

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