I had a very bad first impression. As another person mentioned here, the working environment is very disturbing. They have a central area where all the engineers are crammed in, just like an assembly line. The desk area was messy (lots of wires) and people were sitting next to each other. I understand being a team player and having a need to work at close proximity, but the setting at LinkedIn is not at all private. No cubicle walls, just literally an assembly line setup. As I walked to the conference room, I was pretty much decided on not working at this place. If you want to work with someone, then you can always invite them in your cubicle, or if more than two people need to work, then use a conference room. I, for one, need a personal space to work and I don't want to look at other people's clutter. I was confident and didn't care much at this point. The first guy asked me some basic prepared questions on binary trees. After answering the question, I would ask a counter-question just to gauge their technical skills. I asked him about his thoughts on getting or making a balanced binary tree and the importance of randomized algorithms. The guy couldn't carry the discussion. It was fun, though.

Binary tree traversal.