I was contacted by a recruiter to join an all-day group interview. During the interview day, I joined the short tour. Then we were divided into groups each has 3 people, and we have 4 groups in a room with 3 or 4 interviewers. They send out the problem description. There are 3 problems and 1 to 2 pages of description for each problem. After reading the description, each person chose the problem to solve. There is no obvious difference on the difficulty among the problems. So choose the one that you feel most comfortable to solve. If you have conflict with your teammates, I think it's the best time to show your leadership. We had the brief lunch in the same room while coding. During the interview, an interviewer will take you to another room to have an individual talk. They mostly ask you questions about your thoughts and solutions for the problem you are doing. And sometimes they may ask your understanding of the other two problems which your teammates are working on. My suggestion is that don't be panic about the long problem description. Talk to your teammates or interviewers to improve understanding. Start coding until you have a thorough understanding. Solution may not be perfect, but you should at least implement a brute force version and know how to optimize it.