These interview questions are administrated by everyone at Google, so I just picked one used on me after assuring that it wasn't in any public database. The pro

These interview questions are administrated by everyone at Google, so I just picked one used on me after assuring that it wasn't in any public database. The problem is apparently significantly harder than what interviewers typically get, I didn't know that when I picked it. However I don't think it is a bad question, seeing people struggle with hard problems gives a lot of strong signals as well. Also compared with other interviewers I tend to be on the nicer side of grading, so it is not like getting a hard problem hurts them.