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feat: solved day 12 part 2 🥳

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Stevan Freeborn
2024-12-13 22:01:35 -06:00
parent 9af08b3193
commit a68edab14c
7 changed files with 268 additions and 178 deletions
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12/GardenGroups.Tests/RegionTests.cs
+11
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@@ -31,4 +31,15 @@ public class RegionTests
await Assert.That(result).IsEqualTo(0);
}
[Test]
public async Task AddPosition_WhenCalled_ItShouldAddAPosition()
{
var region = Region.From('A');
region.AddPosition(new(0, 0, 'A'));
await Assert.That(region.Positions).IsEquivalentTo(new HashSet<Position>() { new(0, 0, 'A') });
await Assert.That(region.Area).IsEqualTo(1);
}
}
12/GardenGroups/Direction.cs
+9
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@@ -0,0 +1,9 @@
namespace GardenGroups;
record Direction(int Xd, int Yd)
{
public static readonly Direction Up = new(0, -1);
public static readonly Direction Down = new(0, 1);
public static readonly Direction Left = new(-1, 0);
public static readonly Direction Right = new(1, 0);
}
12/GardenGroups/Garden.cs
+112
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@@ -0,0 +1,112 @@
namespace GardenGroups;
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 positionsToVisit = new Queue<Position>();
positionsToVisit.Enqueue(position);
while (positionsToVisit.Count is not 0)
{
var currentPosition = positionsToVisit.Dequeue();
if (visitedPositions.Contains(currentPosition))
{
continue;
}
region.AddPosition(currentPosition);
visitedPositions.Add(currentPosition);
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);
}
}
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);
}
}
}
}
12/GardenGroups/Position.cs
+29
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@@ -0,0 +1,29 @@
namespace GardenGroups;
record Position(int X, int Y, char PlantType)
{
public Position GetNextPosition(Direction direction) => new(X + direction.Xd, Y + direction.Yd, '.');
public bool TryGetNextPosition(Direction direction, string[] grid, out Position nextPosition)
{
nextPosition = GetNextPosition(direction);
var isOffGrid = IsOffGrid(nextPosition, grid);
if (isOffGrid)
{
return false;
}
nextPosition = nextPosition with { PlantType = grid[nextPosition.Y][nextPosition.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;
}
}
12/GardenGroups/Program.cs
+6 -177
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@@ -1,5 +1,7 @@
using System.Diagnostics;
using GardenGroups;
if (args.Length is 0)
{
Console.WriteLine("Please provide a path to the input file.");
@@ -18,183 +20,10 @@ var input = await File.ReadAllLinesAsync(args[0]);
var stopwatch = new Stopwatch();
stopwatch.Start();
var result = Garden.From(input).CalculateFencePriceBasedOnPerimeter();
var garden = Garden.From(input);
var result = isPart2
? garden.CalculateFencePriceBasedOnSides()
: garden.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);
}
12/GardenGroups/Region.cs
+99
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@@ -0,0 +1,99 @@
namespace GardenGroups;
class Region
{
public char PlantType { get; }
public HashSet<Position> Positions { get; } = [];
public int Area => Positions.Count;
public int Perimeter { 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 AddPosition(Position position) => Positions.Add(position);
public void IncreasePerimeter() => Perimeter++;
public int CalculateFencePriceBasedOnPerimeter() => Area * Perimeter;
public int CalculateFencePriceBasedOnSides()
{
// corners is always
// equal to the number
// of sides
var corners = FindCorners();
return corners * Area;
}
private int FindCorners()
{
var numberOfCorners = 0;
foreach (var position in Positions)
{
var hasNeighborAbove = HasNeighborInDirection(Direction.Up, position);
var hasNeighborRight = HasNeighborInDirection(Direction.Right, position);
var hasNeighborBelow = HasNeighborInDirection(Direction.Down, position);
var hasNeighborLeft = HasNeighborInDirection(Direction.Left, position);
// X
// XRX
// X
if (hasNeighborRight is false && hasNeighborAbove is false)
{
numberOfCorners++;
}
if (hasNeighborRight is false && hasNeighborBelow is false)
{
numberOfCorners++;
}
if (hasNeighborLeft is false && hasNeighborAbove is false)
{
numberOfCorners++;
}
if (hasNeighborLeft is false && hasNeighborBelow is false)
{
numberOfCorners++;
}
// XRX
// RRR
// XRX
var nextPositionRight = position.GetNextPosition(Direction.Right);
var nextPositionLeft = position.GetNextPosition(Direction.Left);
if (hasNeighborRight && hasNeighborAbove && HasNeighborInDirection(Direction.Up, nextPositionRight) is false)
{
numberOfCorners++;
}
if (hasNeighborRight && hasNeighborBelow && HasNeighborInDirection(Direction.Down, nextPositionRight) is false)
{
numberOfCorners++;
}
if (hasNeighborLeft && hasNeighborAbove && HasNeighborInDirection(Direction.Up, nextPositionLeft) is false)
{
numberOfCorners++;
}
if (hasNeighborLeft && hasNeighborBelow && HasNeighborInDirection(Direction.Down, nextPositionLeft) is false)
{
numberOfCorners++;
}
}
return numberOfCorners;
}
private bool HasNeighborInDirection(Direction direction, Position position)
{
var nextPosition = position.GetNextPosition(direction);
return Positions.Any(p => p.X == nextPosition.X && p.Y == nextPosition.Y);
}
}
README.md
+1
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@@ -55,3 +55,4 @@ dotnet build
| 09 | [Problem](./09/PROBLEM.md) | [Solution](./09/DiskFragmenter/) | Doing things with indexes is error prone. |
| 10 | [Problem](./10/PROBLEM.md) | [Solution](./10/HoofIt/) | I recognized the solution for this based on pattern from last year. Solved using BFS. |
| 11 | [Problem](./11/PROBLEM.md) | [Solution](./11/PlutonianPebbles/) | Dictionary > List |
| 12 | [Problem](./12/PROBLEM.md) | [Solution](./12/GardenGroups/) | CORNERS == SIDES |