Day 18 solution

I have a very strong feeling that I massively over-complicated this, but it works. I spent a ton of time making sure each component of the problem was implemented correctly so I could quickly identify where things went wrong, and that setup was convenient enough that I just formalized it and left it in. Maybe it'll be useful for another day...

src/main.cs

@@ -35,7 +35,8 @@ else
         "14" => new Day14(),
         "15" => new Day15(),
         "16" => new Day16(),
-        _ => new Day17(),
+        "17"=> new Day17(),
+        _ => new Day18(),
     };
     day.Go();
 }