None of them asked any leet code questions (I was actually looking forward to the silly puzzle questions MS was notorious for at the time because I love those puzzles, even if I think they're bullshit in an interview. Alas it turned out all those questions were basically for PM positions :( ).
The only question I got that seemed particularly bullshitty was at Google, where it was one of those questions where basically you're expected to work out "the trick", it seemed to me to be very gotcha like. But that was just one question among many, across many people.
I've also interviewed many people over the years, and no one has asked any of those stupid questions. They are completely and utterly useless - I see a few comments here saying we're testing for conformance and that has never been involved in any of it, because again it doesn't provide any knowledge of technical skill. As an interviewer you're also aware that the person on the other side of the table is often extremely stressed or nervous. So we understand that you might make mistakes, or stumble on answers, etc - failing to account for such issues simply means potentially discounting good candidates.
As far a whiteboard coding goes, for myself, and I believe many of my co-interviewers a lot of what is actually being looked for is your thinking and problem solving - seriously, I cannot emphasize enough how you should talk through all your reasoning as you write. That allows us to know whether a logic error is a failure to understand/do the correct thing, or just a standard typo-style mistake that everyone does from time to time (again recall we know you're stressed). Also by and large we aren't looking for /perfect/ code (ok, some do but in reality it's worthless metric - I only got this from the gotcha interviewer at G).
Personally my interviewing I often don't care about the language, I'm interested in the solution, and generally accept pseudo code, or your preferred language.
Just a few general tips as an interviewer:
* When asked a coding question, repeat back what you're being asked, you want to confirm it (I've had people try to solve the wrong problem before), and have (where reasonable) some follow up probe/clarification questions.
* Follow on from above coding question. If you're answering on a whiteboard, remember that the interviewers know that the nature of the format means you might make simple/silly/"stupid" mistakes. Listen for any feedback they give you while answering.
* Additional follow on. Another cannot be emphasized enough point. Write test cases for the problem you're solving. Do it before you start the solution. It demonstrates that you understand the need for them, and provides another opportunity to ensure there's agreement on the problem being solved. It also lets you clarify things like the expected API - not part of the actual problem, but something needed for any implementation. Try to make your test cases cover "normal" and edge cases.
* Be aware that if you are nervous, stressed, or worried, the interviewers are aware of that, and know that that can cause errors you wouldn't normally make
* Try to have a reasonable awareness of the job that you're being interviewed for, some of the relevant things the company does/how it does [software dev, engineering, product management, etc], if at all possible. Either so you can ask questions that indicate you have some understanding, or so you can tie in what the company does as it relates to a particular question (if appropriate, don't just shoe horn things in)
* Be polite - this is a "be subservient" thing, this is just if you act like an asshole the interviewer won't like you, and that will impact what they report. I believe it's consistent across FAANGs that immediately post interview every interview send an email that is basically "Yes/No. Reason: .."
* Don't be sexist, racist, homo-/transphobic, or just generally a bigot - I am aware of one woman interviewer having a candidate assume she was an admin, and treated her as such. Another case where a woman was interviewing someone for a position reporting to her, where a candidate asked who his manager would be, found out it was her. Then told her to her face that he didn't think he could work for a woman. That indicates not just incredible sexism, but also just a complete lack of judgement and common sense. The latter alone would warrant a no hire.