I applied on their website and had a call with a recruiter within a week. The next day, he asked me to do a coding challenge. I spent the weekend doing it, and within a day of sending it to them, they said I had impressed them with my work and asked me to fly to SF for a final round. Note that I had to book my own flight and hotel, and I didn't get reimbursed until two weeks later. Not a big deal, but be prepared to front about $1,000 if you're coming from the East Coast on such short notice.

The onsite wasn't very organized; people stepped in and out. I met with all engineers (besides a brief chat with the recruiter), in total about 8-10 people. I know for a fact I didn't do well on one interview. The interviewer had a very strong European accent, and I also answered one of his questions wrong. He even laughed at me, which I thought was extremely rude. I did well on all the other interviews throughout the day.

A week later, I got a rejection email saying that they liked my passion but didn't think I had enough Python experience. Very much a canned rejection email.

Pretend I am a 5-year-old and explain what an NP-complete problem is.