I interviewed at their Super Day which was a final round of 3 interviews- behavioral, technical, and case. Technical was not too hard. It was LC easy and medium. The case interview was something I had never done before, but it also wasn't too bad. They gave me a scenario and some numbers and asked me to walk them through my thought process.
It was great. Smart people, had good questions, and really tried to do what was best for me. They were very professional and I'm very appreciative of that. I would interview again if I could, just for the experience!
Interview questions [1]
Question 1
Given a "clickstream" (a series of events that customers do on the website or app), create a "quick response model" that provides the most likely actions a user might want to take.
Received an email to interview for their summer internship and was then flown out to interview at C1's HQ in McLean (this was pre-pandemic). No prior contact other than a resume drop.