Meta Software Developer interview questions

A friend of mine working there referred me to the recruiter. The recruiter promptly contacted me to set up a phone interview and asked me what I want from my career and if I like fast paced working environment. Everything was very smooth and professional. The phone interview lasted about an hour and I was asked to write codes on some collaboration editing web site like google doc. The problem to solve and a couple of function headings were already given in the web page. The question was about the binary tree. I was supposed to write a function to return the next node in inorder traversal sequence. In itself, it looks complicated but, there was a funciton heading called, init(), that you can use to preprocess and add any data structure you need. I somehow missed this initially and found this too late :(

Contacted by a recruiter.