Amazon Interview Process - Mid-level Software Engineer

I interviewed for an Amazon SDE II role in July 2026. There were four rounds: DSA, LLD, HLD and a Bar Raiser.

Round 1: DSA

Two questions, both fairly easy.

Question 1: Aggressive Cows (binary search on the answer). I spotted the pattern and solved it without much trouble.

Question 2: Last Stone Weight, framed as chocolates. Each turn you pick the two heaviest. If they weigh the same, both are destroyed. Otherwise the smaller one goes and the difference is put back. Return the last weight left, or 0. A max heap solves it.

Round 2: LLD (the round that cost me)

Question: Design Splitwise

I started the usual way: clarifying questions, functional requirements, core entities, then classes and interfaces. The interviewer stopped me and asked for API design first, which caught me off guard. My prep had been all OOP, design patterns and concurrency.

I defined APIs for creating groups, managing members, adding expenses and splitting them. On Add Expense they asked how the request flows through the system to the database. That turned into data flow, schema and table design, and how expenses are stored, so closer to HLD. I never got to the class-level design I'd planned, and the feedback afterwards confirmed this was my weak round.

Round 3: HLD

The question was tied to the team I was interviewing for, Returns.

Question: Design a package routing system for returned items. Returned packages arrive at a warehouse. Some are repairable or resellable and need to go to the right fulfillment center, and several centers can support the same product category.

I asked clarifying questions, listed requirements, estimated QPS and storage, then walked through the architecture. The interviewer was happy with it, and we went deeper into single points of failure, backpressure, reliability and component failures. This round went well.

Round 4: Bar Raiser (DSA + Leadership Principles)

Question 1: an easy problem I solved quickly.

Question 2: Word Ladder. I used BFS: generate every one-letter neighbour, keep the ones in the list, track visited words and stop at the target.

The LP questions went well. I had real examples ready.

Outcome

DSA, HLD and the Bar Raiser went well, LLD less so. The recruiter told me I wasn't moving forward because of the LLD round. Disappointing, but I learned a lot.

Takeaways

• LLD isn't always classes and interfaces. Be ready for API design, request and response shapes, database schema and how a request reaches the database.

• Don't get attached to your plan. If the interviewer steers somewhere else, adapt.

• In HLD, expect follow-ups on failures, backpressure, scalability and reliability.

• Prepare Leadership Principle stories with real examples for the Bar Raiser.

Good luck to everyone preparing!