This is sounds like a very pretty typical software engineer interview process. The fact that these kinds of interviews suck, don't produce good hires, and yield a ridiculous amount of false negatives has been beaten to death.
Unless you're Google (or Facebook), you are not getting thousands of applications a day. You don't need to emulate their hiring process. They do it for a reason (practicality) whereas it seems others do it out of pure snobbery. Whiteboard coding is worthless (barring simple fizzbuzz tests which can be done over the phone anyway). I mean how pompous does this shit sound:
"All candidates eventually figure out that they will need to add an auxiliary data structure that maintains a map from a 32 bit integer to a 64 bit pointer, because of the aforementioned ten pound sack. Do they know that there are off-the-shelf map classes? If not, do they have confidence that they could write one?"
Eric Lippert is originally from Microsoft though, so I guess that shouldn't surprise me. After all, they're the ones that started asking "Why is a manhole cover round?" in software engineering interviews.
Much respect goes to tptacek that outlines a much better and enlightened alternative.