Meta Software Engineer 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 :(

I had one phone interview with HR-person and one interview with technical guy. Interview with HR consisted of checking my personal details and what I want to do on FB (backend or frontend). After one week I had technical interview with 2 problems. It was my first phone interview. I failed to complete tasks. First problem: - Given array find 3 elements in array that sum up to 0 Second: - You have array of elements of 3 types. How would you sort them?