From the post in question:
> [screening portion] The bulk of the time is spent on coding exercises. The interviewer will send you a link to a collaborative editor and ask you to solve some programming problems.
> We will ask you to do a lot of coding during the interview process, because programming ability tends to correlate strongly with how well people perform as employees. We even have a large set of take-home questions. It can't hurt to check them out and maybe solve a couple before you even submit your resume.
> Take your time preparing. Do code katas and practice interviewing with friends. Try solving the interview questions on our site.
> Hard training makes for an easy battle. Brush up on techniques that you may not use every day, but are very useful when you need them: recursion, graph theory, tree traversal, combinatorial problems, etc.
> You might be asked to implement some well-known library functions.
Being asked to implement some well-known library functions is why I said re-re-re-implement merge-bubble sort-reduce. The rest is why I said FB seems more interested in this than anything else on the list.
Code katas? Take-home questions? Maybe it isn't this way in practice, but the post certainly makes it sound like a bizarro SAT. Needing to "prep" and "practice" coding questions in the way encouraged seems rather odd to me.