Very hectic interview process! too many people, too much time.. no good questions though!
Many of them like to go with puzzles! To a certain extent it is good. But, puzzles should not be a decision maker in selecting the ideal candidate. Test them on the subject specialization.
Seem like they are trying to implement the "Google" interview style which is going to backfire on them eventually!
Personally, I thought they are asking these questions because they must have been tested the same way before getting hired! So, why not take it out on the next incoming individual!
Felt like, my years long expertise did not matter to them! I would not work for them, atleast in this specific group!