I was reached out by an interviewer for the automation framework team (QA) and completed an OA. Then, I was scheduled an interview with a software engineer manager. The problem was that the interviewer was very unprofessional. He showed up late to the meeting, skipped my intro, and kept a condescending tone throughout the entire interview. It went about 30 minutes overtime, and it was clear to me that he was working on something else during my interview, as he would do things like take phone calls and loudly type on his keyboard. I tried to communicate my thought process while solving the problem, and he would either ignore me or say, "Yeah, do that then," while looking at something on his other screen. His only feedback was that he was very disappointed in my solution and that I was just trying random approaches and waiting to be lucky. Not sure why someone so unprofessional is interviewing for anyone - I'd hate to have that guy as my manager.

Optimize on space complexity, which would need to be done using DFS.