Adv2015/D23.1/Program.cs

using System;
using System.Collections.Generic;
using System.IO;

namespace D23._1
{
    public class Machine
    {
        public static uint[] Registers { get; set; }

        public Machine() => Registers = new uint[2] { 0, 0 };

        static public int I { get; set; }

        public readonly Dictionary<string, Action<int, int>> OpCodes = new Dictionary<string, Action<int, int>>
        {
            { "hlf", (r, o) => Registers[r] /= 2 },
            { "tpl", (r, o) => Registers[r] *= 3 },
            { "inc", (r, o) => Registers[r] += 1 },
            { "jmp", (o, _) => I += o - 1 },
            { "jie", (r, o) => { if (Registers[r] % 2 == 0) I += o - 1; } },
            { "jio", (r, o) => { if (Registers[r] == 1) I += o - 1; } },
        };

        public List<(string, int, int)> Code = new List<(string, int, int)>();

        public void AddLine(string op, int p1, int p2) => Code.Add((op, p1, p2));

        public bool Exec()
        {
            (string op, int p1, int p2) = Code[I];
            OpCodes[op](p1, p2);
            I++;

            return I < Code.Count;
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length < 1) throw new ArgumentException();
            if (File.Exists(args[0]) == false) throw new FileNotFoundException();

            var pc = ParseFile(args);

            while (pc.Exec()) ;

            Console.WriteLine($"Part 1 answer is {Machine.Registers[1]}");

            Machine.Registers = new uint[] { 1, 0 };
            Machine.I = 0;

            while (pc.Exec()) ;

            Console.WriteLine($"Part 2 answer is {Machine.Registers[1]}");
        }

        private static Machine ParseFile(string[] args)
        {
            var pc = new Machine();
            using (var file = File.OpenText(args[0]))
            {
                while (true)
                {
                    var line = file.ReadLine();
                    if (line == null) break;

                    var lr = line.Split(" ", 2);
                    var op = lr[0];
                    var vlr = lr[1].Split(", ");

                    int p1 = vlr[0] == "a" ? 0 : (vlr[0] == "b" ? 1 : int.Parse(vlr[0]));
                    int p2 = vlr.Length > 1 ? int.Parse(vlr[1]) : 0;

                    pc.AddLine(op, p1, p2);
                }
            }

            return pc;
        }
    }
}