I attended a university recruiting event. First, there was a phone interview, followed by an on-campus interview in four stages.

The phone interview was behavioral. However, at the on-campus interviews, I was asked to provide hacks, mostly on tricky algorithmic questions.

I got through all the steps but didn't receive a job offer. As far as I understand, you have to give (or at least be on the way to giving) decent answers in all of your interviews. If even one recruiter hesitates, they will look for someone else.

Questions are not always hard by themselves, but most of the time what matters is how you approach the problem and in what way you could improve the code.