秘书问题

Miss Moneypenny You need to hire a secretary. There are n possible candidates to interview and you want to find thebest, the most talented. The problem is that there is great demand for secretaries, so if you want to make sure that you get one you' ll have to offer her the job on the spot. Once she walks out of the door she's gone. You start interviewing candidates one after the other, they can all be ranked, so thisone is better than that, or that one is worse than another, etc. There are no ties. But the order in which they are interviewed is random. What is the best strategy for maximizing the probability of getting the best secretary?