AdventOfCodeDay7.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace AdventOfCodeDay7
{
	class Program
	{
		static void Main(string[] args)
		{
			var input = new List<string>();
			var sr = new StreamReader("../../input1.txt"); // select part one or two here.
			string line;
			while ((line = sr.ReadLine()) != null)
			{
				input.Add(line);
			}

			var wires = new List<Expr>();

			foreach (var w in input)
			{
				var expr = new Expr();
				var parts1 = w.Split(new[] { " -> " }, StringSplitOptions.None);
				expr.Name = parts1[1];
				var parts2 = parts1[0].Split(' ');

				if (parts2.Length == 3)
				{
					expr.Operands.Add(new Item(parts2[0], null));
					expr.Operands.Add(new Item(parts2[2], null));
					expr.Operator = parts2[1];
				}
				else if (parts2.Length == 2)
				{
					expr.Operands.Add(new Item(parts2[1], null));
					expr.Operator = parts2[0];
				}
				else if (parts2.Length == 1)
				{
					expr.Operands.Add(new Item(parts2[0], null));
					expr.Operator = "EQUALS";
				}
				wires.Add(expr);
			}

			int cnt = 0;
			while ((cnt = EvaluateAll(wires)) > 0)
			{
				var done = wires.Where(a => a.Value != null).ToList();
				var notDone = wires.Where(a => a.Value == null);

				foreach (var nd in notDone)
				{
					foreach (var operand in nd.Operands)
					{
						foreach (var d in done)
						{
							if (operand.SValue == d.Name)
							{
								operand.Value = d.Value;
							}
						}
					}
				}
				Console.WriteLine(cnt);
			}

			Console.WriteLine("a = " + wires.FirstOrDefault(a => a.Name == "a").Value);

			Console.ReadLine();
		}

		public static int EvaluateAll(List<Expr> wires)
		{
			var unsolved = wires.Where(a => a.Value == null);
			foreach (var w in unsolved)
			{
				var c = 0;
				foreach (var o in w.Operands)
				{
					ushort n;
					if (ushort.TryParse(o.SValue, out n))
					{
						c++;
						o.Value = n;
					}
				}
				if (w.Operands.All(a => a.Value != null))
				{
					w.Value = Evaluate(w.Operator, w.Operands);
				}
			}
			return wires.Count(a => a.Value == null);
		}

		public static ushort Evaluate(string oper, List<Item> operands)
		{
			if (operands.Count() == 2)
			{
				switch (oper)
				{
					case "AND":
						return (ushort)(operands[0].Value.Value & operands[1].Value.Value);
					case "OR":
						return (ushort)(operands[0].Value.Value | operands[1].Value.Value);
					case "LSHIFT":
						return (ushort)(operands[0].Value.Value << operands[1].Value.Value);
					case "RSHIFT":
						return (ushort)(operands[0].Value.Value >> operands[1].Value.Value);
				}
			}
			else if (operands.Count() == 1)
			{
				switch (oper)
				{
					case "EQUALS":
						return operands[0].Value.Value;
					case "NOT":
						return (ushort)(~operands[0].Value.Value);
				}
			}

			Console.WriteLine("oh noes, something's wrong!");
			return 0;
		}

		public class Expr
		{
			public string Name { get; set; }
			public ushort? Value { get; set; }
			public List<Item> Operands { get; set; } = new List<Item>();
			public string Operator { get; set; }
		}

		public class Item
		{
			public Item(string s, ushort? v)
			{
				SValue = s;
				Value = v;
			}

			public string SValue { get; set; }
			public ushort? Value { get; set; }
		}
	}
}