Interviewer gives you the problem, and word after word you realize it's this LC Medium number 6281 that you crammed 3 times already. What should you do?

1. Admit you've done it already.
   1.1. Interviewer gives you another one
   1.2. Interviewer says OK, why don't you walk me though the solution real fast then

2. Pretend you heard it for the first time just now
   2.1. Pretend wanting to start from naive, and then very smartly work your way to the optimal solution as if you had the idea just now, with a lot of "Oh! If you notice that, then... it's giving me the idea to..."
   2.2. Pretend thinking for a few minutes and getting stuck, and then blast out the optimal solution like you're some kind of Einstein (but with crystal clear thought process explanation)

Please vote what you think one should do, and the expected outcome.