The test isn't about whether you know the algorithm – quite the opposite. The test is about seeing how you approach a problem you haven't (possibly) solved before.
This is what everybody who employs a vanity interview question tells themselves. You can use this logic to justify any question, and the result is an entirely subjective interview process that occasionally and randomly admits candidates based on their knowledge of trivia.
That's an interesting observation. So what you are saying is that if I make sufficient headway into the problem without providing the most efficient answer, it should be fine?
There are rumors that unless you are spot on perfect in Big 4 interviews, they wont advance you.
It all depends on the interviewer. Anyone claiming different is selling you bullshit. The purpose of the interview and how they are actually used in practice is all on the interviewer.
It depends on the aptitude for problem solving that the interviewer observes in the process.
It's about understanding the computer science fundamentals in order to keep your code from burning up 1000's of cores due to asymptotically-poor characteristics.
I mean, aren't those algorithms developed by CS professors/researchers/Ph.D's/mathematicians? As a junior developer I seriously doubt I'd even approach the problem the same way as the super smart person who developed that algorithm.