Adv2018/D9.2/Program.cs

using System;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;

namespace D9._2
{
    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length < 1) return;
            if (File.Exists(args[0]) == false) return;
            var file = File.OpenText(args[0]);

            var text = file.ReadToEnd();
            var matches = new Regex(@"(?<players>\d+) players; last marble is worth (?<points>\d+) points")
                .Match(text);

            UInt64 lastMarble = UInt64.Parse(matches.Groups["points"].Value) * 100;
            int players = int.Parse(matches.Groups["players"].Value);

            var scores = new UInt64[players];

            var currentMarble = new Marble();
            currentMarble.CounterClockwise = currentMarble;
            currentMarble.Clockwise = currentMarble;

            int currentPlayer = 1;
            for (UInt64 marble = 1; marble <= lastMarble; ++marble)
            {
                // ------- Winning case --------

                if (marble % 23 == 0)
                {
                    scores[currentPlayer - 1] += marble;
                    var sevenCounterClockwiseMarble = currentMarble
                        .CounterClockwise
                        .CounterClockwise
                        .CounterClockwise
                        .CounterClockwise
                        .CounterClockwise
                        .CounterClockwise
                        .CounterClockwise;
                    scores[currentPlayer - 1] += sevenCounterClockwiseMarble.Value;

                    sevenCounterClockwiseMarble.CounterClockwise.Clockwise = sevenCounterClockwiseMarble.Clockwise;
                    currentMarble = sevenCounterClockwiseMarble.Clockwise;
                }

                // ------- Cas nominal ---------

                else
                {
                    var oneClockwise = currentMarble.Clockwise;
                    var twoClockwise = oneClockwise.Clockwise;

                    var newMarble = new Marble()
                    {
                        CounterClockwise = oneClockwise,
                        Clockwise = twoClockwise,
                        Value = marble
                    };

                    oneClockwise.Clockwise = newMarble;
                    twoClockwise.CounterClockwise = newMarble;

                    currentMarble = newMarble;
                }

                currentPlayer += 1;
                if (currentPlayer > players) currentPlayer = 1;
            }

            UInt64 max = scores.Max();
            Console.WriteLine($"Result is : {max}");
        }

        class Marble
        {
            public Marble CounterClockwise { get; set; }
            public Marble Clockwise { get; set; }
            public UInt64 Value { get; set; }
        }
    }
}