Of course, there might have been a couple of times when you or your colleagues in the same position needed to prove a theorem or implement a complex algorithm from scratch, but is it enough to include this problem in your interviewing process? If your team has encountered this problem only a few times, it deserves to be a supplementary question at most. Create most of the interview questions from the most frequent problems that your team solves daily. By no means search the web for interview questions. Your interview should be as specific as possible and generic questions will make it dull and unrelated to what you are searching for.
A frequent source of questions is the interviewer's own knowledge resources. You ...