Question was not hard especially if you practice Leetcode questions. I suggest to have leetcode subscription so that you can get access to bloomberg most frequently asked questions. The interviewer was overall nice and patient. The only thing which i didn't like is that she was late and she didn't prepare her question and this COSTED me chance of doing well. it looked like someone else prepared the question and gave it to her. She struggled with explaining how we come up with outputs on a given inputs and honestly even now i still don't understand very well the main question and i believe it is the reason why i failed. After like 15min trying to understand question together, we came up with designing a data structure of a nested list which can also have another nested list inside. Based on the information she gave me, I personally think the question was about to create all subsets for a given input array of numbers. But again this is NOT what she gave me and even after interview i am still confused.