Pergunta de entrevista da empresa AppNexus

Given this (drawn-on-whiteboard) binary search tree, write a method that determines whether it's properly sorted. This is a question to see if you're comfortable with recursion, with low-level data structures, etc. If you don't get this question, you'll likely get a similar one (how does a TreeSet work; please explain how HashMap is implemented; performance of various collections for insertions, updates, deletions, etc.).