Citi Interview Question

Hash map, heap, in-depth data structures, multi-threading, scaling and more. In-person interview is a grilling session. If they have already selected a candidate, they will simply kill time and laugh on you by asking their day to day issues. The interview was supposed to be 1 hour but the interviewing panel appeared to be free as they conducted it for 1hr 30 min and were asking if I have some more time. Their behavior was childish, they make faces and laugh as if there is some inside joke going on. I am glad I did not work there as the work environment didn't appear appealing. It was way negative and demoralizing!