The projects are .NET Core 2.2 Console Applications that output either graphics or strings to the Console when run. Every day is a separate solution and in most cases I keep the first and second part of a problem to have no dependencies inbetween them. Sometimes this makes for a lot of repeated code from the first part (I just copy/paste and change what's needed) or that they are combined somehow like in day 18's problem. This ensures that mostly the first part will always run no matter whatever I have to change to adapt it to the second part. Also, you sometimes get to see a pretty radical change in parts like for day 12 where the first part is solved in about 200 lines of code and the second in about 50 but is less(?) readable.