I disagree with this. I can solve the majority of leetcode hard problems in under an hour despite not having seen them before and I'm far from the smartest person I've met.

Congratulations, you've memorized leetcode patterns. Proves nothing beyond that (except that you've also had the time recently to practice leetcode).

I have never practiced leetcode puzzles or memorised solutions to them. I don't understand why you jumped to this conclusion.

Probably because you said you "can solve the majority of leetcode hard problems in under an hour". That could easily give the impression that you have practiced them. If you haven't practiced them, then how do you know you can solve them?

Sample of 5-6 I tried for fun. Along with a handful of similar puzzles from other places.

Under an hour is... not enough time for an interview. Needs to be under 20-30 minutes given that most interviews are 60 minutes and the other 20-50% is taken up by other conversation.

I don't know you or the people you've met, but if you can do this without studying the questions before and the solutions are performant, then I would put you in the "very smart" category

If someone claims they can solve Leetcode hard problems without studying the questions and the solutions beforehand, then I would put them in the "full of shit" category

You had to know this was going to get a lot of downvotes.

However, I have a real question as a follow-up: Have you been able to profit from this skill? If true, you should be able to crush any "whiteboard" programming interview. If I had it, I would move every 2-4 years and get large pay rises. You should definitely be able to pass FAANG interviews with that skill.

    > Many of those questions were thesis/publication-worthy decades ago when first solved

The hare and tortoise (cycle detection via Floyd's) is a legendary impossible interview question. It wasn't solved until the 1960s with a PhD thesis. It is a hard problem to face in an interview. I had seen it twice in my career. I failed the first time. The second time I had the answer memorised, then put on my very best Morgan Freeman stage acting to pretend I was discovering the answer during the interview. What a joke. I was laughing to myself as I was "stumbling" towards the answer while the interviewer was providing minor hints.