I had scheduled one phone interview of 1 hr. 30 minutes of questions about my research. He asked about my research and as I was walking through my projects he was interupting me and asking questions about why and how I have approach that problem and solve the challenge, which falls into many general ML concepts and some more specialized in Deep learning. around 5-6 minutes of behavioral questions and at last he asked me to code a question with multiple follow up questions on time and space complexity and improving the algorithm. They invited me to on-site interview 5 days later.
On site interview was pretty intense. It starts at 9 with 30 minutes of Amazon specific behavioral questions which I consider them very specific and not easy to answer and then he gave me one codoing question (LC medium) in around 25-30 minutes, (pairwise swap). [I tried to solve it itervatively for 10 minutes and I could not so I move to recursive and with some hints I finished the code though if I had seen the question before it was a piece of cake]. right after that I had one hr presentation of my research to a commitie of 5 people(some of my interviewers). It went for 1 full hour. Then I had a machine learning design question. Interviewer asked me a specific issue that they had in AWS and asked me to solve it. Again a tough interviewer who went to very detail questions such as R2 formulation and many other detail concept of 1tailed and 2tailed t-test and .. Then I had one hour lunch break which was just a lunch and gap with the host. After lunch I had one another round of interview, 30 minutes behavioral and then bombard with a lot of detail questions about all the possible concepts in machine learning and deep learning , very very detailed and complex , ranging from why - when RMSE over MAE to how to handle drop out in test time and many more. It was literally an intense interview. He cut me many times soon after he asked a question and he realized I know the concept and I am starting very confident. It was like he was grid searching through all the possible topics in deep learning, ML to find my weak spot. it went for 1 hour fix. the forth intervirwe was again asking a lot about ML-deep learning and stat this time. and last interviwer which was the manager of the team asked me behavioral question for an entire 1 hour. All those people were smart and seasoned and I enjoyed talking to all. I rank the interview hard and lenghty. My recruiter called me next day around noon, very nice and polite and gave me the rejection news, event though I fairy answered all of the questions and would give myself 90/100 score. I would guess I have not done well in my behavioral even though I practiced a lot or maybe they wanted a more experinced person for that research position. I got quick answer probably because I told them I have a pending offer and need to decide soon.