Ok, for starters I didn't get any SQL questions at all. The person who commented above me got the same interview questions as me. The improve this code one was me given a nested loop(so n^2 runtime), and then they asked me how I would go about improving this code's runtime. The given code is a brute force solution so you'll probably be fine. Hopefully that gives more detail about the question. As for leetcode/other stuff, I don't think that really helps tbh. I mean, these questions were not difficult by any stretch. The fact that you even know what leetcode is and are probably using it tells me you probably have enough skill to get the questions right. Unfortunately, it's pretty common to ace a technical and still get rejected. Just try to keep your head up, these are tough times.