Microsoft Developer interview questions

First was an online test with three easy problems. The first one was to find a bug in a function(it was to change an and condition to an or condition or something like this), the second one to convert a string of binary digits to an int and the third one was a very easy greedy algorithm. After that, there were three interviews one after the other. The first one was started with behavioral questions then a technical problem(not really algorithm), then system design, then to implement a concurrent hash map(also had to implement the linked list). Code didn't need to run, but it needed to be clear. The system design was the bad one for me. I couldn't understand what the interviewer said, he didn't seem to understand my questions(I had to implement a system that sells vehicles and I asked how many vehicles are expected to be sold and he said all of them) and he gave no feedback if I was on the right track or not. He talked very little while I did the design.