First question was fine, but I feel that I could have done better if I had more practice on design skills. Overall, was not difficult but probably I could have done better if I had more regular hands on experience or concepts with the system design related topics. Second question, my first solution was correct but not best in performance since I made it quickly, then the new requirement was to improve the time complexity of the solution which took me a bit of going back and forth but with few tips from the interviewer, we did it. At the end, he had another solution in mind using another data structure that I didn't considering using because initially, the array was expected to have duplicates but the solution the interviewer had in mind would change that so the array is expected not to have duplicates. I got the hint later on that this is what he had in mind later; but here there is nothing really to do except practicing more solving such challenges and try to do better next time.