A recruiter contacted me via email or LinkedIn; I can't recall exactly. They asked if I would be interested in Google. I have a long resume and a somewhat specialized set of skills in embedded systems, so I said I'd give it a go, but I wasn't sure how my skills would be useful at Google. They waived the phone screen and moved me directly to an onsite interview. They sent a list of topics to cover to prepare for the interview, which looked like something out of a college computer science course. I was very busy at my current job, so I had little time to go over it, but it was fun revisiting basic algorithms and data structures.

Onsite consisted of 3 x 45-minute one-on-one interviews, lunch, and 2 more 45-minute sessions. All were back-to-back with no breaks other than lunch.

• 1st session: The interviewer introduced himself and gave me time to introduce myself for the first 10 minutes. He then asked two questions. The first was about arrays and didn't require writing code; the second was about dynamic programming and asked for code. I did well on both, so we had 10 more minutes to spare where I asked him questions.
• 2nd session: The introduction took a really long time. The interviewer spoke at great length about himself and his work. He asked if I was interviewing for real or just there to get interview experience, as he apparently did the same initially. When we got to the question, there was only about 15 minutes left. It was a tree-related question that, in my opinion, wasn't really presented very well. Code was required. I started solving it, but he was basically walking me through every step. I'm not sure if he just wanted me to pass or realized he had already spent too much time talking. I got the correct solution, but I felt like I was being led to it.
• 3rd session: An embedded systems engineer asked me a lot about my actual resume. In the end, he asked a pretty basic, embedded system-specific question and asked me to write code. It was very easy for me, and I did really well. This was probably the most enjoyable session.
• Lunch: This was the weirdest part of the day. The interviewer only got notified the night before and didn't seem eager to be there. He didn't even know where the closest cafeteria was. We ended up walking for about 15 minutes around the campus. I dropped my tray when getting food and spilled lunch on my clothes, which was upsetting. He then suggested we sit outside because it was quieter there. However, the day was hot, and it was really uncomfortable, so I was glad to get back inside.
• 4th session: Usual introductions. A general distributed systems question. It went pretty well in my opinion, but I am not a distributed systems specialist, so I can't really judge.
• 5th session: This was the worst one of the day. Usual introductions. Two questions. The first question was supposed to be a warm-up, a really simple bit manipulation task, but for some reason, my brain just froze; I'm not sure if it was stress or the sun from lunch. I worked manually through some samples and did come up with an algorithm and a correct solution. The interviewer corrected something in my solution, but when I started running it through a test case, it turned out my initial code was correct, so we reverted it. Because the first question took so much time, we only had about 10 minutes for the second one, which was supposed to be the main question, so we didn't really finish it.

The recruiter called me a week later, saying they decided not to proceed with my candidacy at this time. I'm not too bothered since I'm happy at my current job, and this was more of a learning experience, but I admit that if they had made me a good offer, I would have seriously considered it.

While driving home, I did come up with a really good solution to that unfinished question from the 5th session. I also found every single question asked in my interview on programming websites. It looks like if I hadn't been so busy and had spent more time preparing, the interview would have gone much smoother. I thought my experience alone would be enough to pull me through.

Other than the lunch person and the 2nd session interviewer, everyone else was very pleasant and enjoyable to talk to.

All were unexpected.

I didn't prepare for any, but was able to work through most of them.

None were really difficult under normal circumstances.