I’ve had this happen to me before and disclosed it during the interview. Consistently, the response was the interviewer telling me they were impressed that I was well prepared, and to go ahead with the answer.
The vast majority of your coworkers will have gone through a similar if not identical interview process. Do you prefer to work with people that pretend they've never seen a question before when they have? Then do that. Do you prefer to work with people that admit they have seen the question before but are not directly penalized for it? Then do that. If you somehow are penalized for it... you dodged a bullet.
As an interviewer, I would prefer (in this order):
1. The candidate has actual domain experience matching the question and can rattle off the answer in their sleep. We can use the remaining time to go deeper into the question and probe the boundaries of candidate's knowledge. [maybe 1 out of 200 candidates actually deliver this]
2. The candidate came prepared, studied the question ahead of time, can rattle off the answer from memory. As above, with the question out of the way, we could use time to explore around the topic and find areas the candidate didn't study but still can work their way through. It's rare that you see someone who memorized a perfect answer, but then can't go further purely because they have no canned response.
3. The candidate doesn't know the question ahead of time, and legitimately "thought hard" and solved it on the spot. We may or may not have time to probe further, but candidate has shown the ability to reason through a problem outside their domain.
[above this line is my "hire" bar, below is unfortunately the vast majority of candidates]
4. The candidate doesn't immediately get there, but can be guided through with hints and can follow the bread crumbs I'm laying.
5. The candidate tries but, for many possible reasons, struggles, goes off down wrong-way roads, and doesn't make any progress.
6. The candidate freezes up, deer in headlights, won't produce anything.
7. The candidate talks and talks with a prepared speech about his background and skills, but doesn't actually do or solve anything [yes, I've seen this multiple times]
I usually asked as an interviewer if you had seen the material before. If you were honest, it was very impressive, you could give your solution, and we could also cover other material.
