DraftKings Senior Software Engineer interview questions

I just went through the entire interview sequence for a Senior/Lead iOS Developer role over at DraftKings and thought it would be useful to recap how it was and my experience, just to help future candidates coming down the chute. I spoke with the recruiter three or four times. One time as an introduction, the second time was interview prep for the "virtual on-site", then the last encounter which I'll talk about at the end of this recap. All video interviews are done doing Microsoft Teams (DK only recently dropped using Zoom for their conference calls), but they still do internal communication via Slack. All technical interviews have HackerRank whiteboards and coderpads available to work with. The first interview (with a lead dev) is a straight coding session. This was the standard "given an array of customers & total revenue, discounts & their amounts, and types of discounts being offered to customers" problem, which I'll try to detail as completely as possible below. This one seemed to go really smoothly (I just loaded a bunch of arrays and implemented the validation rules and explained myself as I went along), and I got the call the next day inviting me to do the "virtual on-site". The virtual on-site can potentially eat up four hours out of a business day, but in my case they split it up one interview on one day and then the last three on the next day. The system design interview session basically had the candidate designing an odds provider/serving system for DraftKing players. I dutifully sketched out how I would do it and felt relatively good about the conversation, though apparently the person interviewing me didn't feel the same. The next interview was covering Team Dynamics with the director (or the guy one level above the hiring manager), and this is where I was asked the standard "are you a team player" and "tell me about when you failed and how you recovered" questions that are part of most behavioral & cultural interviews. The director did provide much more context about the role I was interviewing for -- DK is trying to migrate everything to individual & native SDK's and frameworks (I think delivered via Swift Package Manager) from the legacy (and increasingly difficult to work with) Xamarin codebase. I recall the director saying the size of the team was five when I spoke with the director, it will be six by the time this recap gets published, and they hope to eventually have at least 9 or 10 developers on the team. The current breakdown was 3 android, 1 iOS, 1 lead who is doing iOS and then the new iOS developer that was joining. So with that relatively small number I'm guessing think the director was referring to the Player Account Management team and not to the entire mobile organization. I got to speak with the hiring manager next, and his topic was a "deep dive" in some project/technical history, where I had to explain some amazing feature I had worked on in the past, how I implemented it, how I interacted with various people (e.g. project managers or product owners, UX/UI designers, backend devs and then collaborating with Android devs on my team to make sure iOS & Android were behaving the same in parallel). My last technical interview was the "Object Oriented Design Exercise", and basically had me implement how to structure how chats would be displayed and the underlying data dealt with. This one ended up being the one that likely got me disqualified, but I'll detail below. The last day of the week (one day after their internal recap session) the recruiter called me back to give me the official thumbs down. I am very grateful that the recruiter did provide relatively detailed feedback as to where and how I goofed up: the two technical interviews of the "virtual onsite" I apparently didn't provide enough detail or perhaps I sounded shaky -- and while I won't console myself with this as an excuse, I still believe I did okay given that this was my first set of hardcore interviews post pandemic and I've been out of practice for a couple years. But hopefully my experience flunking the process will help you prepare for interview success, especially if you are aiming for a Mobile (iOS) role on the mobile team. If my notes did help you to prepare for your interview, please let me know by clicking on the "helpful" link below (as this motivates me to try to be as detailed as possible).

I had a recruiter reach out to me on LinkedIn, and we had a regular phone call to discuss my experience and other relevant topics. The recruiter mentioned that they would send further instructions after the call but then went silent for a week. At that point, I thought the communication had come to an end. However, to my surprise, I received an invitation for the first interview. It followed the typical pattern that everyone describes, where I had to write a function to validate input on HackerRank. The task itself was relatively straightforward, but I struggled a bit with the extensive task description. Nevertheless, the interviewer was amazing - incredibly friendly and supportive! Shortly after, I was invited to a "virtual onsite interview." It consisted of three separate interviews: team dynamics, deep dive, and OOD (Object-Oriented Design). The team dynamics interview was more of a classic behavioral interview, with questions like "Tell me about a time..." The interviewer was interested in understanding my approach to tasks and my previous experience working in a team. The deep dive interview was a bit unclear to me. It involved a few technical questions but lacked depth. Some behavior questions were also thrown into the mix. The OOD interview focused on system design, which is what you typically expect at companies like MAANG. The recruiter promised to come back with feedback by the end of the next day and then ghosted. That was a bit disappointing even though I knew from Glassdoor that it is common for the company. (If not ghosting I would say the overall experience was positive)