I was referred by a friend who interned at IBM. Before that, I had already submitted my CV to their online recruitment system, but I seriously doubt it was useful.

There was a one-hour phone screen with two interviewers simultaneously. They asked some simple coding and behavioral questions. After that, they were interested enough to invite me to an on-site interview, but I still had to push them a bit because my other interviews were approaching, and I needed to schedule them quickly.

I was invited to the IBM Watson office. At IBM, almost every employee has a separate office room, so I met each interviewer in their own office. The interview started early, and there were about eight interviewers (I lost count, and they didn't send me the schedule either). Each lasted for one hour, except for the one who took me to lunch, so the entire process was quite tiring.

One week later, I sent a follow-up email to HR but only received silence. Then, after another two weeks, I sent another follow-up email to the manager and some interviewers and finally heard from them that I was no longer being considered.

Almost every interviewer asked me to introduce my background and previous works, and then pick the part he was interested in to go further.

Besides that, only one interviewer asked me algorithm questions, and maybe two asked questions about C++ language. All the remaining questions were general behavioral questions.

There was one interview with two interviewers from the security department. I assume it was some kind of security measure, since they obviously had fewer professional backgrounds.