An interview is not a fairness competition. They are rarely fair and subjective. The end goal of any interview is to enter into a contract which exchanges money for time. The setting of an interview is an informational asymmetric paradigm. Your one sided fairness won’t make the process fair.

You may still want to keep letting your interviewer know that you solved the question before. However, this doesn’t make the process fair. It’s a story that you’re probably telling yourself to make it feel better ;)

99% of people (as a person who's done interviews a while ago) never say "I've seen this before" -- either because they're lying or never seen it before or don't remember.

When you say "I've seen this before" you put the interviewer on edge and derail his interviewing flow, he's going to second guess every answer you give -- "has he seen this one also?" and might switch to really obscure questions that actually disadvantage you as an honest interviewee.

Then when he'll make his final appraisal of your score he'll put a big question mark over your result and might go for someone with lower scores but that he feels has never seen those questions before.

To be clear, I'm not talking about obvious questions like "how can you determine if a linked list has a loop without aditional data structures" -- where you either know Dijkstra's solution or you don't, and can't possibly come up with the solution on the spot.

It's not the same. The parking lot isn't a competitive game. You can't enforce fairness unilaterally in a competitive game. The people who benefit from your actions in the interview case are the people who are willing to take advantage.

In a game where everyone is "cheating", you can cheat to be on even ground or you can not cheat and be at a disadvantage. You don't have a way to make the game fairer.

(btw I wouldn't lie in the interview either, I just don't agree with how you're applying the concept of fairness)

Me neither - but you if you want to work for FAANG, or wannabe FAANGs - you're going to have to get used to it.

In fact, arguably that is the very purpose of these "tests" - to get you to compromise your integrity and negate your gut intuition about how professionals should treat each other -- even before you are invited to come in for an interview,

surely that only results with a good methodology for choosing people. If whiteboarding and testing are inherently flawed following the correct process would not reliably lead to a better team (unless of course the test then shows honesty), because if it did reliably lead to a better team it would show the process was not flawed.

However, your approach does not result in a fairer process or a better team. That would only be true if everyone behaved like you.

In fact, you're condemning the teams you don't take a job with to have more dishonest people in them! But only by such a small margin that it really won't affect anything.