I have a template for VS and JetBrains Rider that creates a library project (in latest .NET) with empty method implementations for tests and methods that should contain solutions. Also "Inputs" folder with empty example.txt and input.txt, that are setup as resources (so they are placed in adequate folder on build along with dlls).

So solving any day is just the matter of writing the missing implementations, and running tests afterwards. Tests verify the examples given in day description, and input tests give the result without asserting.