The interviewer lacked basic CS knowledge. Specifically, I had a function that just removed a singular item from a python set (hashset) and said it ran in constant time. On the other hand, the interviewer was aggressively condescending about how set removal is linear, falsely believing it requires iteration through all the items. Amortized constant time operations for hashtables/sets is one of the most basic and core concepts presented in any intro CS sequence -- a quick google search easily reveals thousands of articles explaining it. The fact that he criticized me for his own lack of fundamentals knowledge is absurd. Other aspects of the interview were similar to those who also had negative experiences. Multiple signs indicated the interviewer was very disengaged. For example, at one point we moved onto another question and in the middle of my solution explanation, he jumped back to a piece of code I had written 5 minutes earlier. Furthermore, at multiple points I could hear the shuffling of papers/I don't know what over the phone and he sounded very bored. On a positive note, recruiters were quick to schedule rounds.