Advent of Code 2018 Day 3

aoc2018_3.cs

	class Day3_2018 {
		const string INPUTFILE = @"2018\day3.txt";

		public void Part1() {
			var input = File.ReadAllLines(INPUTFILE);

			var dimension = 1000;
			var area = dimension * dimension;
			var fabric = new int[area];

			foreach (var line in input) {
				var match = Regex.Match(line, @"#(\d+)? @ (\d+)?,(\d+)?: (\d+)?x(\d+)?");

				var id = Convert.ToInt32(match.Groups[1].Value);
				var x = Convert.ToInt32(match.Groups[2].Value);
				var y = Convert.ToInt32(match.Groups[3].Value);
				var w = Convert.ToInt32(match.Groups[4].Value);
				var h = Convert.ToInt32(match.Groups[5].Value);

				for (var row = y; row < y + h; row++) {
					for (var col = x; col < x + w; col++) {
						var i = (row * 1000) + col;

						fabric[i]++;
					}
				}
			}

			var total = 0;

			for (var i = 0; i < area; i++) {
				if (fabric[i] > 1) {
					total++;
				}
			}

			Console.WriteLine(total);
		}

		public void Part2() {
			var input = File.ReadAllLines(INPUTFILE);
			var claims = new Dictionary<int, Claim>();

			var dimension = 1000;
			var area = dimension * dimension;
			var fabric = new int[area];

			foreach (var line in input) {
				var match = Regex.Match(line, @"#(\d+)? @ (\d+)?,(\d+)?: (\d+)?x(\d+)?");

				var id = Convert.ToInt32(match.Groups[1].Value);
				var x = Convert.ToInt32(match.Groups[2].Value);
				var y = Convert.ToInt32(match.Groups[3].Value);
				var w = Convert.ToInt32(match.Groups[4].Value);
				var h = Convert.ToInt32(match.Groups[5].Value);

				claims.Add(id, new Claim(x, y, w, h));
			}

			var claimed = new List<int>();

			foreach (var claim in claims) {
				for (var row = claim.Value.Y; row < claim.Value.Y + claim.Value.H; row++) {
					for (var col = claim.Value.X; col < claim.Value.X + claim.Value.W; col++) {
						var i = (row * 1000) + col;

						// If this space was already claimed, make sure we track the existing claim ID and the new claim ID.
						if (fabric[i] > 0) {
							claimed.Add(fabric[i]);
							claimed.Add(claim.Key);
						}

						fabric[i] = claim.Key;
					}
				}
			}

			claimed = claimed.Distinct().ToList();

			var found = new List<int>();

			for (var i = 0; i < area; i++) {
				if (fabric[i] > 0) {
					if (!claimed.Contains(fabric[i])) {
						found.Add(fabric[i]);
					}
				}
			}

			found = found.Distinct().ToList();

			// Ideally this prints out only one number.
			Console.WriteLine("Found: " + string.Join(", ", found));
		}

		class Claim {
			public int X { get; set; }
			public int Y { get; set; }
			public int W { get; set; }
			public int H { get; set; }

			public Claim(int x, int y, int w, int h) {
				X = x;
				Y = y;
				W = w;
				H = h;
			}
		}
	}