I've taken the idea of your framework and expanded on it by allowing for multiple years.
My updated project structure is as follows:
+---AdventOfCode
| AdventOfCode.csproj
| GlobalUsings.cs
| Program.cs
|
+---2015
| | Day_01.cs
| | Day_02.cs
| | Day_03.cs
| |
| \---Inputs
| 01.txt
| 02.txt
| 03.txt
|
+---2021
| Day_01.cs
| Day_02.cs
| Day_03.cs
|
\---Inputs
01.txt
02.txt
03.txt
I've taken the idea of your framework and expanded on it by allowing for multiple years.
My updated project structure is as follows: