feat: stalled on day 12 part 2

2024-12-13 10:24:59 -06:00
parent cf310c6630
commit cd9527d722
3 changed files with 334 additions and 2 deletions
@@ -1,2 +1,200 @@
-// See https://aka.ms/new-console-template for more information
-Console.WriteLine("Hello, World!");
+using System.Diagnostics;
+
+if (args.Length is 0)
+{
+  Console.WriteLine("Please provide a path to the input file.");
+  return;
+}
+
+if (File.Exists(args[0]) is false)
+{
+  Console.WriteLine("The provided file does not exist.");
+  return;
+}
+
+var isPart2 = args.Length is 2 && args[1] is "part2";
+var input = await File.ReadAllLinesAsync(args[0]);
+
+var stopwatch = new Stopwatch();
+stopwatch.Start();
+
+var result = Garden.From(input).CalculateFencePriceBasedOnPerimeter();
+
+stopwatch.Stop();
+Console.WriteLine($"The total cost to fence the garden is {result}. ({stopwatch.ElapsedMilliseconds}ms)");
+
+class Garden
+{
+  private static readonly Direction[] Directions = [
+    Direction.Up,
+    Direction.Down,
+    Direction.Left,
+    Direction.Right,
+  ];
+  
+  private readonly string[] _grid;
+
+  private Garden(string[] grid)
+  {
+    _grid = grid;
+  }
+
+  public static Garden From(string[] input) => new(input);
+  
+  public int CalculateFencePriceBasedOnSides()
+  {
+    var visitedPositions = new HashSet<Position>();
+    var total = 0;
+    
+    WalkGarden((x, y) =>
+    {
+      var currentPosition = new Position(x, y, _grid[y][x]);
+
+      if (visitedPositions.Contains(currentPosition))
+      {
+        return;
+      }
+      
+      var region = FindRegion(currentPosition, visitedPositions);
+      total += region.CalculateFencePriceBasedOnSides();
+    });
+
+    return total;
+  }
+  
+  public int CalculateFencePriceBasedOnPerimeter()
+  {
+    var visitedPositions = new HashSet<Position>();
+    var total = 0;
+    
+    WalkGarden((x, y) =>
+    {
+      var currentPosition = new Position(x, y, _grid[y][x]);
+
+      if (visitedPositions.Contains(currentPosition))
+      {
+        return;
+      }
+      
+      var region = FindRegion(currentPosition, visitedPositions);
+      total += region.CalculateFencePriceBasedOnPerimeter();
+    });
+
+    return total;
+  }
+
+  private Region FindRegion(Position position, HashSet<Position> visitedPositions)
+  {
+    var region = Region.From(position);
+    var regionPositions = new HashSet<Position>();
+
+    var positionsToVisit = new Queue<Position>();
+    
+    positionsToVisit.Enqueue(position);
+
+    while (positionsToVisit.Count is not 0)
+    {
+      var currentPosition = positionsToVisit.Dequeue();
+      
+      if (visitedPositions.Contains(currentPosition))
+      {
+        continue;
+      }
+      
+      regionPositions.Add(currentPosition);
+      region.IncreaseArea();
+
+      foreach (var direction in Directions)
+      {
+        if (
+          currentPosition.TryGetNextPosition(direction, _grid, out var newPosition) is false ||
+          newPosition.PlantType != currentPosition.PlantType
+        )
+        {
+          region.IncreasePerimeter();
+          continue;
+        }
+        
+        positionsToVisit.Enqueue(newPosition);
+      }
+    }
+    
+    // TODO: Do something here to identify how many
+    // sides each position contributes in a region
+    
+    return region;
+  }
+  
+  private void WalkGarden(Action<int, int> callback)
+  {
+    for (var y = 0; y < _grid.Length; y++)
+    {
+      var row = _grid[y];
+
+      for (var x = 0; x < row.Length; x++)
+      {
+        callback(x, y);
+      }
+    }
+  }
+}
+
+class Region
+{
+  public char PlantType { get; }
+  public int Area { get; private set; }
+  public int Perimeter { get; private set; }
+  public int Sides { get; private set; }
+
+  private Region(char plantType)
+  {
+    PlantType = plantType;
+  }
+
+  public static Region From(char plantType) => new(plantType);
+  public static Region From(Position position) => new(position.PlantType);
+  
+  public void IncreaseArea() => Area++;
+  public void IncreasePerimeter() => Perimeter++;
+  public void IncreaseSize() => Sides++;
+  public int CalculateFencePriceBasedOnPerimeter() => Area * Perimeter;
+
+  public int CalculateFencePriceBasedOnSides() => Area * Sides;
+}
+
+record Position(int X, int Y, char PlantType)
+{
+  public bool TryGetNextPosition(Direction direction, string[] grid, out Position nextPosition)
+  {
+    var x = X + direction.XD;
+    var y = Y + direction.YD;
+
+    nextPosition = new(x, y, '.');
+
+    var isOffGrid = IsOffGrid(nextPosition, grid);
+
+    if (isOffGrid)
+    {
+      return false;
+    }
+    
+    nextPosition = nextPosition with { PlantType = grid[y][x] };
+    return true;
+  }
+  
+  private static bool IsOffGrid(Position position, string[] grid)
+  {
+    return position.X < 0 ||
+           position.X > grid[0].Length - 1 ||
+           position.Y > grid.Length - 1 ||
+           position.Y < 0;
+  }
+}
+
+record Direction(int XD, int YD)
+{
+  public static Direction Up = new(0, -1);
+  public static Direction Down = new(0, 1);
+  public static Direction Left = new(-1, 0);
+  public static Direction Right = new(1, 0);
+}