I did really enjoy that coding challenge, though. Good job with it. It is the one thing I did like about the whole experience, and I still share it with people when they ask about what a good coding challenge might be. Tree traversal isn't particularly useful in web dev world, but it's a pretty intuitive task, so I think it's gives good insight into whether a programmer can reason logically about a task.

I'd rather see real-world challenges, though. Sometimes that's hard, though, depending on the company.