I was referred to TripAdvisor by a friend. Got called by the technical recruiter and easily set up the first phone call. Came in and talked to 3 engineers. About 75% of the discussion was around technical questions: looking at code, writing code, explaining algorithms. The last 25% were around things that I found (technically) interesting. The questions were difficult, but fair. I had picked up an algorithms book in the prior week to prepare myself and that was tremendously helpful.