Amazon L6 (Alexa) Interview Experience (Role : SSE, Location : Boston))

OA [DSA coding + System Design MCQ + work style survey]: 2 coding questions were asked - one simple set-based and the second similar to the largest rectangle in histogram type but a little harder. 3 Project simulation where each had multiple questions which required knowledge of system design basics and work experience. These were like arrange given options in priority-type questions. Many work styles survey MCQ questions. Round 1 (1hr 15 mins)[HM + team fitment + design]: Started with intro and asked about current work and company questions [20-25 mins] Then asked 5-6 questions based on LPs (Customer Obsession, Deliver results) [20-25 mins] Ended with a design question. The expectation was to explain the algo that would best fit to meet the requirements. [25-30 mins] The design question was to explain the algo used for token systems in banks. How the tokens would be distributed and how requests would be served on a first come first basis. Expected time to wait for each token. Token numbers would be unordered during distribution. (Solved it using 2 queues in O(1) time.) Round 2 (1hr)[System Design (HLD+LLD)]: The round started with an intro and was asked about hobbies. Then the interviewer gave a question about the backend design of 1 common product of Amazon that their team works on. The question was not direct but a small part of the product. I was asked to explain the algo of how to do it. I explained the algo and logic using the map-reduce concept and the interviewer was quite impressed. Later I was asked to write down functional/non-functional requirements and draw HLD architecture on envision app. I listed 6-8 Functional requirements out of which I was asked to focus on 3 requirements. Also, I mentioned the scale and number of users that I would be considered for the design. Drawing architecture took 15-20 mins as it was quite big. Later I was asked to change the open source components/frameworks in design with AWS services. I could do a few but later I was allowed to use google search to search for the remaining components. Then I was asked to calculate the expected cost of the design and then optimize the design. I was surprised as such questions are asked for senior roles. I politely said that I never used these AWS services before and only used open-source frameworks. The interviewer was okay and later moved on to LLD. In LLD, I was asked to design the class diagrams and relations between classes. Due to the time limit, I couldn't complete LLD completely but was able to explain a few classes and design patterns used in them. The interviewer was very impressed overall and later mentioned that there are 240 engineers working on this design problem. Round 3 Bar Raiser(1hr )[DSA coding]: Started with an intro about work experience. Was asked 2 coding questions- 1st question was something similar to two sum problem on the binary tree. It was easy and did it in 10 mins. 2nd ques was a leetcode stack of medium-level questions. Explained the logic and wrote the code. Missed 1 corner case but soon identified and fixed it. Dried run the code in 4-5 test cases. Then I was asked 2 questions on LPs and the round ended. Round 4 (1hr 20 mins)[DSA coding]: None of the questions in this round were from leetcode or any popular website. 2 coding questions were asked: 1st question was a map-based question of the array. Solved and coded. The interviewer was a little strict and asked concepts in-depth about code, time and space complexity, and collision handling. 2nd question was hard level type question from CodeChef. It was a big but easy-to-understand question and I was asked to write 3 pre-given functions. The question was an update-query type question on N-arry tree. I started with brute force solution, optimized it to the sub-optimal solution, and then explained the most optimal solution which involved topo sort + segment tree/Lazy propagation. The interviewer asked to code the sub-optimal solution and was happy with it. Then some discussion on time and space complexity which was fairly easy to calculate. Then I was asked 1 question based on LP and the round ended. Result: The next day recruiter called me and said I'd cleared all the rounds. Feedback was that I had missed the corner case in Round 3 which I fixed later, else everything was perfect. Received the comp details after a week as the recruiter went on leave in between. TC - 466K (L6) #amazon #interview #boston