[penguinduck]

Regarding the first, I think they basically do this to test how "programming smart" someone is. Like my boss tells me when I interview, "determine potential". However, I agree that this shouldn't disqualify someone for a more technical kind of job. For me it is more of a "if he is really smart we should hire him despite the fact he is perhaps unqualified, he will easily learn" thing. The disqualifying questions are easier than this one.

Regarding the second, I agree completely. This problem is good because it doesn't give an advantage to rote memorization of basic CS from college (unlike asking about red-black trees etc), but when stolen from the internet and reused becomes bad because it gives an advantage to something worse - googling questions and memorizing answers.

I assume (or hope) Google switches up the problems they use all the time and hopefully doesn't use automated testing (because I care how someone thinks, not just whether they produce the solution in X minutes), but since you interviewed at a different company perhaps it is a cargo cult effect: Google has some of the smartest programmers and they asked this, so obviously we should also ask the same thing! Cargo culting is extremely common in IT in less-established companies, my workplace is not immune to it either. Pick things a super-successful company does that require almost zero investment, effort or true change, and copy those. It is ridiculous.

Of course, the things these companies really do right, they are too much effort, let's just copy them in superficial ways and hope for the best!