My Operations Research Scientist Interview Experience at Amazon

How to prepare for each round

Earlier this year, I received an interview invitation from Amazon for the role of Operations Research Scientist at their Luxembourg office. The invite came with a link to suggest possible time slots for the first round of interview.

I was super excited when I saw the mail! I was looking to move to the EU, and had Amazon LUX on my radar! So I went ahead and gave a few options for scheduling the first round of interviews.

The First Round — HR Round

I also reached out to a few friends at Amazon for a heads-up on what I’d be facing in the first round.

They told me that the first round was going to be an HR round, where the recruitment partner would try and understand if my profile fits what they are looking for. So it would be more of a conversation than an interview.

So all I had to do was go through my own resume and prepare to narrate my experience in each of the projects I had worked on. So the ball was in my court.

On the Day of the call

The recruitment partner called me to ask for high-level details on my experience in Operations Research. I gave him a detailed description of my work profile, and he found it to be a fit for what they were looking for. So he told me that he would put me through to the second round.

He also told me that the nature of the round would be technical, and would be conducted by the hiring manager.

The Second Round — Hiring Manager

In this round, you will face your hiring manager, who is generally the person you would report to, if you get hired. So this round is going to be very technical. Generally, it has some deep dives into the technical details of your previous projects, along with a caselet.

So it would help to brush up your basics. Most of the cases are based on basic principles of the technology, but with twists. This is where they assess whether you’re able to handle the curve-balls.

Preparation

I got a few weeks’ worth of gap between the first and second round. So, I took my time to brush up on some heuristics and some exact methods. For this, I used the course on Discrete Optimisation, delivered by the faculty from the University of Melbourne.

I also went through some classic lecture videos on Youtube. I did some research on the specific OR problems that this particular team in Amazon was working on, and started reading up some recent publications as well as standard problem formulations for those problems.

On the Day of the call

One the day of the interview, luckily, I faced no shocks. The deep dives on the projects I had worked on went well. This was the part of the interview that I could drive based on how much detail I provided for each project.

Then came the caselet. This was a smooth ride too, since I took to the first principles and formulated the entire model, including the curve-ball constraints he threw at me.

The Presentation Round

In two days I received a mail from the recruitment partner that I cleared the round and have to make a technical presentation on any topic of my choice (alternatively, I could pick a paper from my Ph.D.)

Preparation

Choosing a good topic for presentation turned out to be a bigger challenge than I had expected. I had two topics to choose from and I was very confused. One belonged to some problems I had solved at work, and another was from my Ph.D. I found the two topics equally interesting, but I didn’t know which one would capture the recruiter’s attention.

After a lot of thinking, I prepared my presentation on the technical problems I had solved at work. That gave me enough meat to go on for 45 minutes, which was the suggested duration for the presentation.

On the Day of the presentation

The entire OR team attended the presentation. I presented the problem I had solved at workplace. Since I had worked in the airline domain, it was a new industry for them. They were all interested and asked a lot of questions.

I answered them all, and they were pretty happy with the fact that I had introduced them to the problems in a different industry. Personally, I felt that I did okay, but the feedback was very encouraging.

The next day was the day of the five back-to-back rounds.

The Third to Eighth Round — Bar Raiser and Others

There would be 5 back to back rounds of interviews with different stakeholders in the team — a Senior OR Scientist, Engineering Manager, Data Science Manager, Hiring Manager, and an OR Scientist from a different team.

Preparation

Since I do not have any formal coding background, I was very nervous about the coding round. So, I practiced multiple interview questions, and went through many online resources (I enrolled on HackerRank, Code Chef, Leet Code, as well as a course from Udemy).

It was a little too much, given I had only three weeks to prepare the presentation as well as prepare for the other five rounds. But I had to put a hard stop after 10 days of practice.

I was extremely worried for data structures because I knew it needed a lot of practice than I could do. However, that was all I could do in order to balance the time for preparing for the other rounds.

On the Day of the interviews

I had five rounds scheduled over a span of six hours, with one 45 minute break thrown in for lunch.

Coding Round

This is was the first round, and my most dreaded round. This was conducted by an Engineering Manager. The interview went on for roughly an hour. The interview consisted of two coding questions, one on logic and another on data structures.

The logical questions went something like ‘how do you convert a number given as a string, into an integer type’, and then there were some corner cases discussed. All in all, I solved it.

The data structures one was a bummer. It was about left binary trees. I had zero idea. I learnt about what it was IN THE INTERVIEW, and still tried to solve for a few cases. We ran out of time while I was struggling with the corner cases. Sigh.

I felt very bad for not having completed it, but hey! This wasn’t the time to sulk. Had four more rounds to go. I powered through.

OR Round

This was conducted by a Senior Operations Research Scientist from my ‘possible future’ team. He asked me a few questions about model formulations, and some constraints to solve a business problem. I went through this without any hiccups. The problem was a modified version of network optimisation model.

I just had to fall back on first principles. It turned out pretty well.

Behavioural Rounds

The following three rounds were behavioural in nature. They were all supposed to be answered in alignment with one of the 14 Leadership Principles of Amazon.

One of the three rounds revolved around how I worked in a team (Was I a team player or a lone wolf? What was my communication style?)

The second one was about how I dealt with uncertainty (Describing a situation where project specifications changed mid-way, and how I handled it. A situation where you came up with an idea and realised your approach wasn’t the best/was wrong.)

The last one was about Customer Obsession. (A time when I prioritised customer’s experience over the tasks at hand/business in general.)

This ended my recruitment process. I was told I’d get my feedback within five working days.

Phew! The most challenging part was over. Now for the wait!

The Verdict-The Feedback

Within five days from the final rounds I received a call from the recruitment partner. I was told that my performance was great on all aspects, but my coding skill was not up to the mark (I knew this because I do not have a coding background). The level of experience they were looking for was higher than I had. He said he would reach out to me if a junior position opened up.

I was a little disappointed, but deep down, I knew I had applied for a senior position. So I took the feedback and started working on it. Maybe after a few years, when I feel confident about it, I’ll apply again!

Conclusion

From my experience at Amazon, I felt that the team was trying to throw challenges at you to see how you adapt to them. And at companies like Amazon, or any other company in Europe I have applied for, the interviews are always crafted not only around testing your hard skills, but also around how you work with your team and across multiple teams.

So just being good at what you do won’t cut it. You need to be a good team player as well. Additionally, it helps to be culturally aware and have the ability to negotiate (trust me, this is an extremely desirable skill if you have to work with stakeholders, and more often than not, YOU WILL HAVE TO!)

Do prepare yourselves around these aspects as well.

All the best!