I had a ~45-minute phone interview where I was basically asked why I wanted to work there and to describe a project I'd worked on. Then I took a brutal ~3.5-hour online exam, which had a few logic questions and then four coding problems. After that, because of COVID, I spent four hours chatting with various people. There was a little bit of testing at this stage, but no code (mostly asking how you'd approach something). Everyone was very nice and respectful.

Given a matrix detailing interactions at a party and an infected person, find everyone who was potentially infected at the party.