Adv2015/D06.2/Program.cs

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

namespace D06._2
{
    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length < 1) throw new ArgumentException();
            if (File.Exists(args[0]) == false) throw new FileNotFoundException();

            var regex = new Regex(@"(?<verb>turn on|turn off|toggle) (?<x1>\d+),(?<y1>\d+) through (?<x2>\d+),(?<y2>\d+)");

            const int size = 1000;
            var lights = new int[size, size];

            using (var file = File.OpenText(args[0]))
            {
                while (true)
                {
                    var line = file.ReadLine();
                    if (line == null) break;

                    var result = regex.Match(line);
                    (int x, int y) p1 = (int.Parse(result.Groups["x1"].Value), int.Parse(result.Groups["y1"].Value));
                    (int x, int y) p2 = (int.Parse(result.Groups["x2"].Value), int.Parse(result.Groups["y2"].Value));
                    var verb = result.Groups["verb"].Value;

                    for (int x = p1.x; x <= p2.x; ++x)
                        for (int y = p1.y; y <= p2.y; ++y)
                        {
                            switch (verb)
                            {
                                case "turn on": lights[x, y]++; break;
                                case "turn off": lights[x, y] = Math.Max(lights[x, y] - 1, 0); break;
                                case "toggle": lights[x, y] = lights[x, y] += 2; break;
                            }
                        }
                }
            }

            var answer = 0;
            for (int x = 0; x < size; ++x)
                for (int y = 0; y < size; ++y)
                    answer += lights[x, y];

            Console.WriteLine($"The answer is : {answer}");
        }
    }
}