He asked me if I were to design windows, as in like the file explorer windows and image windows, what data structure would I use. He asked me how would clicking windows work. He then asked me what if I had countless number of these windows, how would my implementation need to change. He then asked me how to measure the Big-O of my data structure and some other efficiency questions. *Advice - talk to them through the process, use sudo code (the less time you waste on syntax the better cause they don't care), ask them lots of questions to clarify what they want.
