I am a bit suspicious in this regard of algorithm questions for which the interviewer already has an answer. The interviewer may have a solution in hand that t

I am a bit suspicious in this regard of algorithm questions for which the interviewer already has an answer. The interviewer may have a solution in hand that they never solved themselves, or solved at their leisure in a different context (e.g. not in front of several people using a marker board with dried up markers). That said, an interview in isolation is sometimes an attempt to get a sense of how a person reacts under pressure or constraints. It is doubtful that this really matches with the type of pressure that comes with most jobs.