Amazon WOW Interview Experience for SDE 1 (2021)

Amazon announced the women hiring event, Amazon WOW, in 2021. We had to register on the amazon wow portal to access it after which we receive an invitation to the exam.

Written Test:

1. Screening test (1 Easy coding question and computer science fundamentals)
2. Standard Amazon placement Test (Debugging, coding, workstyles assessment, aptitude)

Interview: For SDE 1, there were 3 interview rounds. The exam results were released in December 2021, and rounds of interviews were planned for January through February 2022. Result announcements were made in March 2022.

Round 1: (Technical Interview): Duration: 60 Minutes Platform: Amazon Chime

• This round started with the interviewer asking me to introduce myself. After a quick introduction, I was directly asked the DSA question.
• Problem 1: transform binary search tree to greater sum tree
• I was asked to write a production-level code for the same. I explained my approach, performed a dry run, and stated time and space complexities.
• Problem 2:  find-maximum-possible-stolen-value-houses  I explained my approach using Dynamic programming after which the interviewer extended the problem by stating that the n houses are now in a circular street. I explained my approach, and its time and space complexity completed the code and performed a quick dry run. The interviewer was quite satisfied with this and the round ended with a few behavioral questions.

Round 2: (Technical Interview): Duration: 90 Minutes Platform: Amazon Chime

• I was questioned about one of the projects listed on my résumé to start this round of the interview. After a detailed discussion, the interviewer presented the DSA question.
• Problem 1: Given a matrix with each cell value as ‘A’ or ‘G’ for army and gold respectively, such that we have consecutive army cells followed by gold cells. We have to output the row number that we should choose to steal such that we can encounter maximum gold cells.
• I explained the brute force approach followed by methods to optimize the code. The interviewer gave me a hint which helped me come up with the most optimal solution possible. After completing the coding part for the same, we discussed the time complexity of this approach.
• Problem 2: check-if-a-binary-tree-is-subtree-of-another-binary-tree He simply requested me to explain the strategy for this one and to indicate the time and space complexity for the same because we were running out of time. 
• I asked the interviewer a few questions about his work at Amazon to wrap up this round.

Round 3: (Technical Interview) Duration: 60 Minutes Platform: Amazon Chime

• The manager began round three by asking me a few behavioral questions regarding my projects and internship. These questions are generally related to Amazon’s Leadership principles and you are expected to highlight those qualities while answering them. After a detailed discussion, he presented the DSA problem.
• Problem 1: In a 2D matrix, given source cell ( any matrix corner) and destination cell ( any cell in the matrix), find no cells to be traveled to reach the destination cell such that we can only follow the diagonal path in a spiral fashion ( bottom left and bottom right diagonal paths or top left and top right diagonal paths)
• This round had a single coding question with an easy difficulty level, but I was asked to write the code in such a way that it can be generalized to change the movement either from right to left or left to right with minimum alterations in the code.

Final Verdict: I got an e-mail after almost a month stating that I have been selected as an SDE 1 at Amazon.

Tips:

• Amazon heavily relies on its  12 leadership principles and expects the candidates to reflect these skills. Make sure you note down at least 2-3 leadership principles that align with your work in each of your projects. When responding to the behavioral questions, emphasize these abilities.
• Amazon gives utmost importance to the quality of code you write. A candidate is expected to write production-level code which is clean, and well indented with proper variable names.
• Make sure you are thorough with DSA and OOPs concepts.
• Think loudly throughout the interview process, even when you are coding. Always highlight the time and space complexities of your approaches. 
• Take your time to comprehend the DSA problem and seek clarification by asking questions about it.
• Always exhibit interest in the job at the company by asking the interviewer questions at the conclusion.