I completed the usual rounds: recruiter phone screen, a phone interview, and a full-day virtual on-site.

It felt like it went moderately well. Afterward, the recruiter asked if I could decide within a week if they extended an offer. I stated I would likely need two weeks to complete interviews with other companies. She seemed annoyed and mentioned "consideration for other candidates."

The next day, she emailed, saying things looked positive but her hiring team was out, and she'd look forward to chatting mid-week. There was radio silence for a week.

She then called to say I had "passed the on-site, but someone else accepted an offer already."

It felt like my time and theirs had been wasted.

Lots of BFS and DFS.

Didn't get the dreaded operating systems question, and instead received a system design question.