HR call asking why you are interested in the role, your past experience, sharing a bit about the role, and then if successful, it will go to the next stage.

Pair programming with two engineers on an algorithm for an hour. This was the worst experience I've had so far. At first, a more senior engineer guided the process. I think he got mad or was not satisfied with the answers I gave. He suddenly asked whether I wanted to sort my input array in ascending or descending order in a very loud voice. I think since then, he kept silent during the whole interview without even asking me a single question (obviously because I wasn't giving the correct answer). Then another engineer guided me through the process. But even if a candidate can't get the correct output, do they deserve to be treated like this? The engineer showed no professionalism in conducting the interview, and it was clear he was not interested in hiring me; he just went silent. This is so unprofessional.

Stop wasting your time with companies that are unprofessional in their interview process.

An algorithm about the First Fit Decreasing (FFD) algorithm.