Well, that sounds just weird. Either you expect the people being interviewed as part of their prep to learn and remember forever everything they ever may need a

Well, that sounds just weird. Either you expect the people being interviewed as part of their prep to learn and remember forever everything they ever may need at Facebook and that could possibly be asked in the interview, or your argument doesn't make sense. If I hadn't any contact with parsers/compilers for a while I will need to look stuff up. When you have no frame of reference in my process when getting the information necessary to solve the problem - how can that possibly be a good indicator of me being able to solve an unforeseen problem? If there is a known solution and I already have the exact algorithm, the hard part is over and it's only about writing code. Which is exactly what people seem to complain here: The skill to reproduce a known algorithm is at best the lowest possible bar.