How do I answer a technical interview question I am already familiar with?

Question

To prepare for an upcoming interview, I did some online searching to see what, if anything, previous candidates had to say about the interview at this company.

It seems that all candidates were asked the same particular question, and this question isn't necessarily what one could expect to be a "standard" technical question (i.e it's rather specific to the sort of work the company does, and perhaps unlikely to be found among the slew of common programming interview questions available online and in books; it isn't however too technical or specific to arouse suspicion if one began answering immediately).

I do not want to lie to the interviewers if asked explicitly whether I was aware of the problem beforehand, and nor do I want to "fake" / act like I'm approaching the problem for the first time (i.e. don't want to sit, pondering, murmuring "hmm", before getting up to write on the whiteboard, when I know already where I want to start).

Would it be detrimental to begin the answer by saying something like the below?

So, I actually did some searching and anticipated that this question might be asked. In doing so, I considered a wide array of approaches, and can demonstrate those and their short-comings to arrive at an optimal solution.

I don't want to result to doing this, but it would be uncomfortable having to 'act' like I'm approaching the problem for the first time.

Answer 1

"So, I actually did some searching and anticipated that this question might be asked. In doing so, I considered a wide array of approaches, and can demonstrate those and their short-fallings to arrive at an optimal solution."

IMO that's an excellent answer. To me as interviewer this conveys a bunch of positive things

1. The candidate has not only done some homework to prepare, but the research done was also effective in generating useful information
2. The candidate is honest and transparent. She/he doesn't try to exploit an unusual advantage but engages constructively
3. The candidate has enough confidence to go a bit "off script".
4. The candidate does not only show the "right" answer but wants to show the process to arrive at the answer

Any one of the above would be at least as valuable to me than just having the correct answer. The combo would be a very strong upside. Go for it and good luck !