If you go through a 3 person loop and get 2 problems right and 1 wrong, you might get an offer, but I guarantee that the voting would be two "hire" votes from the questions you aced, and a "no-hire" vote from the one you failed.
There are a couple of reasons for this. The most obvious is that, given two candidates, the better choice will (at least appear) to be the candidate who got the most questions right.
The more common scenario that I have seen is that engineers simply work backwards. If you got the solution wrong (or didn't finish) their thinking will go something like: they got it wrong -> they went down the wrong path since they chose a hashmap instead of a tree -> they are weak in data structures -> no hire
I am at one of the bigger tech companies, and it really is a roll of the dice on if you get a question on a topic you have studied. Especially if you have been out of school for awhile.
The worst part is that bigger tech companies force hiring on the engineers. Hiring candidates becomes part of your own career advancement. If it is a big company, you will go to a day of training and suddenly be a professional interviewer. It is even worse since my opinion (that this system is awful) seems to be the minority. All of my colleagues think they are great at hiring, pontificate over lunch on what makes a good candidate, and discuss their favorite questions (well, their favorite questions from the standard set of questions from the company bank. This is science here, obviously we use standardized questions.)
Of course, if you fail in the interview, you can always come back. It's not like I've ever heard a colleague say, "sigh I am not looking forward to this interview; We've already turned them down once."