I was contacted by one of their recruiters via LinkedIn. I then had two different discussions via phone and an onsite interview.

The first discussion was with the recruiter. It was a short talk where I introduced myself and the recruiter presented me with the job and some details about the IMG group. She didn't tell me anything that wasn't already on the job description. I was also very surprised that she asked me to give names for the clients of the company where I was working at the time. I found it very unprofessional. I told the recruiter that this is confidential information and I cannot give any names apart from those already mentioned on the website.

The second discussion was a technical interview with the hiring manager. It took half an hour but was unbelievably efficient. I was asked questions about my work, about problems that I had to solve, and I had to do some GPU coding.

Next, I was invited for an onsite interview in Cupertino. The onsite interview took two days.

On the first day, I had discussions with four people. One of them was the hiring manager. The interviews from the first day covered subjects related to C, binary representations, parallel access to data structures (queues, if I remember correctly), and then GPU-related topics: reduce, histogram, and implementing a global memory allocator.

On the second day, I had interviews with three people. The subjects were related to GPU algorithms and GPU architecture.

All interviewers had been very professional, but most of them were lacking any enthusiasm and seemed very indifferent. No one told me anything about their team and the project. Of course, I was given the option to ask questions, but only 5 minutes after each interview. I was still expecting a brief introduction from their side.

I had some trouble understanding what one of the interviewers was saying. He seemed to have some small difficulties talking and a non-American accent. I had to ask him to repeat the questions many times, which made me very stressed and nervous. I didn't manage to answer all his questions.

Apple has many offices in Cupertino. For the one where I had the interviews, each day I had to wait outside the building for my first interviewer to come and open the door for me. You cannot enter the building otherwise; you're not allowed to, and there's no waiting room. So be prepared in case it rains outside.

Matrix multiplication on the GPU