2024 Day14 Solved

smabuk · Dec 14, 2024 · adbc21b · adbc21b
1 parent 83462b6
commit adbc21b
Showing 1 changed file with 60 additions and 21 deletions.
diff --git a/Solutions/2024/Day14.cs b/Solutions/2024/Day14.cs
@@ -12,6 +12,7 @@ public static partial class Day14 {
 	[Init]
 	public static void LoadRobots(string[] input) => _robots = [.. input.As<Robot>()];
 
+
 	public static int Part1(string[] _, Action<string[], bool>? visualise = null, params object[]? args)
 	{
 		const int NO_OF_SECONDS = 100;
@@ -20,12 +21,12 @@ public static int Part1(string[] _, Action<string[], bool>? visualise = null, pa
 		int height = args.TilesTall();
 
 		List<Robot> robots = [.. _robots];
-		
+
 		robots.VisualiseMap(width, height, "Initial state:", visualise);
 
 		for (int noOfSeconds = 1; noOfSeconds <= NO_OF_SECONDS; noOfSeconds++) {
 			robots = [.. robots.Select(r => r.MoveNext(width, height))];
-			if (noOfSeconds < 6) {
+			if (noOfSeconds < 6 && height < 50) {
 				robots.VisualiseMap(width, height, $"After {noOfSeconds} seconds:", visualise);
 			}
 		}
@@ -35,50 +36,92 @@ public static int Part1(string[] _, Action<string[], bool>? visualise = null, pa
 		return robots.SafetyFactor(width, height);
 	}
 
-	public static string Part2(string[] input, params object[]? args) => NO_SOLUTION_WRITTEN_MESSAGE;
-
 	private static Robot MoveNext(this Robot robot, int width, int height)
 	{
 		(int x, int y) = (robot.Position + robot.Velocity);
-		if (x >= width ) { x %= width; }
-		if (y >= height) { y %= height; }
-		if (x < 0) { x = width + x; }
-		if (y < 0) { y = height + y; }
+
+		//if (x >= width ) { x %= width;  }
+		//if (y >= height) { y %= height; }
+		//if (x < 0)       { x = width  + x; }
+		//if (y < 0)       { y = height + y; }
+
+		x = x < 0 ? width  + x : x % width; 
+		y = y < 0 ? height + y : y % height; 
 
 		return robot with { Position = new(x, y) };
 	}
 
 	public static int SafetyFactor(this IEnumerable<Robot> robots, int width, int height)
 	{
-		int midX = width / 2;
+		int midX = width  / 2;
 		int midY = height / 2;
 
-		int quad1 = robots.Count(robot => robot.Position.X < midX  && robot.Position.Y < midY);
-		int quad2 = robots.Count(robot => robot.Position.X > midX  && robot.Position.Y < midY);
-		int quad3 = robots.Count(robot => robot.Position.X < midX  && robot.Position.Y > midY);
-		int quad4 = robots.Count(robot => robot.Position.X > midX  && robot.Position.Y > midY);
+		int quad1 = robots.Count(robot => robot.Position.X < midX && robot.Position.Y < midY);
+		int quad2 = robots.Count(robot => robot.Position.X > midX && robot.Position.Y < midY);
+		int quad3 = robots.Count(robot => robot.Position.X < midX && robot.Position.Y > midY);
+		int quad4 = robots.Count(robot => robot.Position.X > midX && robot.Position.Y > midY);
 
 		return quad1 * quad2 * quad3 * quad4;
+	}
+
+
+	public static int Part2(string[] _, Action<string[], bool>? visualise = null, params object[]? args)
+	{
+		int width  = args.TilesWide();
+		int height = args.TilesTall();
+
+		List<Robot> robots = [.. _robots];
+
+		int noOfSeconds = 0;
+		for (noOfSeconds = 1; !robots.IsChristmasTree(width, height); noOfSeconds++) {
+			robots = [.. robots.Select(r => r.MoveNext(width, height))];
+		}
+
+		robots.VisualiseMap(width, height, "Christmas Tree:", visualise);
 
+		return noOfSeconds;
 	}
 
-	public static void VisualiseMap(this IEnumerable<Robot> robots, int width, int height, string title, Action<string[], bool>? visualise)
+	public static bool IsChristmasTree(this IEnumerable<Robot> robots, int width, int _)
 	{
-		const char EMPTY = '.';
+		int midX = width / 2;
 
+		int count = 0;
+		int prevX = 0;
+		foreach (Robot robot in robots.OrderBy(robots => robots.Position.Y).ThenBy(robots => robots.Position.X)) {
+			if (robot.Position.X == prevX + 1 ) {
+				count++;
+				if (count > 10) {
+					return true;
+				}
+			} else {
+				count = 0;
+			}
+
+			prevX = robot.Position.X;
+		}
+
+		return false;
+	}
+
+	public static void VisualiseMap(this IEnumerable<Robot> robots, int width, int height, string title, Action<string[], bool>? visualise)
+	{
 		int[,] map = new int[width, height];
-		//map = map.Fill(0);
 
 		foreach (Robot robot in robots) {
 			map[robot.Position.X, robot.Position.Y] += 1;
 		}
 
 		if (visualise is not null) {
-			string[] output = ["", title, .. map.AsStrings().Select(s => s.Replace('0', EMPTY))];
+			string[] output = ["", title, .. map.AsStrings().Select(s => s.Replace('0', '.'))];
 			_ = Task.Run(() => visualise?.Invoke(output, false));
 		}
 	}
 
+	private static int TilesWide(this object[]? args) => GetArgument(args, 1, 101);
+	private static int TilesTall(this object[]? args) => GetArgument(args, 2, 103);
+
+
 	public sealed record Robot(Point Position, Point Velocity) : IParsable<Robot>
 	{
 		public static Robot Parse(string s, IFormatProvider? provider)
@@ -97,8 +140,4 @@ public static bool TryParse([NotNullWhen(true)] string? s, IFormatProvider? prov
 
 	[GeneratedRegex("""p=(?<positionx>[\+\-]?\d+),(?<positiony>[\+\-]?\d+) v=(?<velocityx>[\+\-]?\d+),(?<velocityy>[\+\-]?\d+)""")]
 	public static partial Regex InputRegEx();
-
-	private static int TilesWide(this object[]? args) => GetArgument(args, 1, 101);
-	private static int TilesTall(this object[]? args) => GetArgument(args, 2, 103);
-
 }