Refactor day 15 solution

Day15 - Lens Library/Day15Solver.cs

@@ -8,11 +8,13 @@ public sealed class Day15Solver : DaySolver
 	public override int Day => 15;
 	public override string Title => "Lens Library";
 
+	private readonly InputReader _inputReader;
 	private readonly IReadOnlyList<string> _initializationSequence;
 
 	public Day15Solver(Day15SolverOptions options) : base(options)
 	{
-		_initializationSequence = InputReader.ReadInitializationSequence(Input);
+		_inputReader = new(options);
+		_initializationSequence = _inputReader.ReadInitializationSequence(Input);
 	}
 
 	public Day15Solver(Action<Day15SolverOptions> configure)
@@ -32,61 +34,14 @@ public override string SolvePart1()
 
 	public override string SolvePart2()
 	{
-		var initializationSteps = _initializationSequence
-			.Select(InitializationStep.Parse)
-			.ToList();
-		var boxes = new List<Lens>?[256];
-		foreach (var step in initializationSteps)
+		var lensConfigurator = new LensConfigurator();
+		foreach (string stepString in _initializationSequence)
 		{
-			int labelHash = HolidayAsciiStringHelper.Hash(step.Label);
-			var box = boxes[labelHash];
-			if (box is null)
-			{
-				box = new(1);
-				boxes[labelHash] = box;
-			}
-
-			switch (step.Operation)
-			{
-				case InitializationOperationType.Remove:
-					// find lens with the same label and remove it
-					box.RemoveAll(lens => lens.Label == step.Label);
-					break;
-				case InitializationOperationType.Insert:
-				{
-					var lens = box.Find(l => l.Label == step.Label);
-					if (lens is null)
-					{
-						lens = new(step.Label);
-						box.Add(lens);
-					}
-
-					lens.FocalLength = step.Parameter;
-					break;
-				}
-				default:
-					throw new InvalidOperationException($"Invalid operation type '{step.Operation}'.");
-			}
-		}
-
-		int focusingPowerSum = 0;
-		for (int boxNumber = 0; boxNumber < boxes.Length; boxNumber++)
-		{
-			var box = boxes[boxNumber];
-			if (box is null) continue;
-			for (int slotNumber = 0; slotNumber < box.Count; slotNumber++)
-			{
-				var lens = box[slotNumber];
-				focusingPowerSum += (boxNumber + 1) * (slotNumber + 1) * lens.FocalLength;
-			}
+			var step = _inputReader.ParseStep(stepString);
+			lensConfigurator.PerformStep(step);
 		}
 
-		return focusingPowerSum.ToString();
+		int totalFocusingPower = lensConfigurator.CalculateFocusingPower();
+		return totalFocusingPower.ToString();
 	}
 }
-
-internal class Lens(string label)
-{
-	public string Label { get; } = label;
-	public int FocalLength { get; set; }
-}

Day15 - Lens Library/Day15SolverOptions.cs

@@ -4,4 +4,7 @@ namespace AdventOfCode.Year2023.Day15;
 
 public sealed class Day15SolverOptions : DaySolverOptions
 {
+	public char SequenceSeparator { get; set; } = ',';
+	public char RemoveOperationChar { get; set; } = '-';
+	public char InsertOperationChar { get; set; } = '=';
 }

Day15 - Lens Library/HolidayAsciiStringHelper.cs

@@ -1,4 +1,4 @@
-namespace AdventOfCode.Year2023.Day15;
+namespace AdventOfCode.Year2023.Day15;
 
 internal static class HolidayAsciiStringHelper
 {

Day15 - Lens Library/InitializationOperationType.cs

@@ -0,0 +1,8 @@
+namespace AdventOfCode.Year2023.Day15;
+
+internal enum InitializationOperationType
+{
+	None = 0,
+	Remove,
+	Insert,
+}

Day15 - Lens Library/InitializationStep.cs

@@ -0,0 +1,8 @@
+namespace AdventOfCode.Year2023.Day15;
+
+internal readonly struct InitializationStep(string label, InitializationOperationType operation, int parameter = default)
+{
+	public string Label { get; } = label;
+	public InitializationOperationType Operation { get; } = operation;
+	public int Parameter { get; } = parameter;
+}

Day15 - Lens Library/InputReader.cs

@@ -1,50 +1,51 @@
-using AdventOfCode.Common.SpanExtensions;
+using AdventOfCode.Common.SpanExtensions;
 
 namespace AdventOfCode.Year2023.Day15;
 
-internal static class InputReader
+internal sealed class InputReader(Day15SolverOptions options)
 {
-	public static List<string> ReadInitializationSequence(string input)
+	private readonly char _sequenceSeparator = options.SequenceSeparator;
+	private readonly char _removeOperationChar = options.RemoveOperationChar;
+	private readonly char _insertOperationChar = options.InsertOperationChar;
+
+
+	public List<string> ReadInitializationSequence(string input)
 	{
-		var sequence = new List<string>(input.AsSpan().Count(',') + 1);
-		foreach (var sequenceSpan in input.AsSpan().Trim().Split(','))
+		var sequence = new List<string>(input.AsSpan().Count(_sequenceSeparator) + 1);
+		foreach (var sequenceSpan in input.AsSpan().Trim().Split(_sequenceSeparator))
 		{
 			sequence.Add(sequenceSpan.Trim().ToString());
 		}
 
 		return sequence;
 	}
-}
-
-internal readonly struct InitializationStep(string label, InitializationOperationType operation, int parameter = default)
-{
-	public string Label { get; } = label;
-	public InitializationOperationType Operation { get; } = operation;
-	public int Parameter { get; } = parameter;
 
-	public static InitializationStep Parse(string line) => Parse(line.AsSpan());
+	public InitializationStep ParseStep(string line) => ParseStep(line.AsSpan());
 
-	public static InitializationStep Parse(ReadOnlySpan<char> line)
+	public InitializationStep ParseStep(ReadOnlySpan<char> line)
 	{
 		line = line.Trim();
-		int operationCharIndex = line.LastIndexOfAny('-', '=');
-		InitializationOperationType operation = line[operationCharIndex] switch
-		{
-			'-' => InitializationOperationType.Remove,
-			'=' => InitializationOperationType.Insert,
-			_ => throw new InvalidOperationException("Invalid operation character.")
-		};
+		int operationCharIndex = line.LastIndexOfAny(_removeOperationChar, '=');
+		InitializationOperationType operation = ParseOperation(line[operationCharIndex]);
 		var labelSpan = line[..operationCharIndex];
 		string label = labelSpan.ToString();
 		var parameterSpan = line[(operationCharIndex + 1)..];
 		int parameter = parameterSpan.IsEmpty ? default : int.Parse(parameterSpan);
 		return new(label, operation, parameter);
 	}
-}
 
-internal enum InitializationOperationType
-{
-	None,
-	Remove,
-	Insert,
+	private InitializationOperationType ParseOperation(char operationChar)
+	{
+		if (operationChar == _removeOperationChar)
+		{
+			return InitializationOperationType.Remove;
+		}
+
+		if (operationChar == _insertOperationChar)
+		{
+			return InitializationOperationType.Insert;
+		}
+
+		throw new InvalidOperationException("Invalid operation character.");
+	}
 }

Day15 - Lens Library/LensConfigurator.cs

@@ -0,0 +1,73 @@
+namespace AdventOfCode.Year2023.Day15;
+
+internal sealed class LensConfigurator
+{
+	private readonly List<Lens>?[] _boxes = new List<Lens>?[256];
+
+	private List<Lens> GetBox(int boxNumber)
+	{
+		var box = _boxes[boxNumber];
+		if (box is null)
+		{
+			box = new(1);
+			_boxes[boxNumber] = box;
+		}
+
+		return box;
+	}
+
+	public void PerformStep(InitializationStep step)
+	{
+		int labelHash = HolidayAsciiStringHelper.Hash(step.Label);
+		var box = GetBox(labelHash);
+
+		switch (step.Operation)
+		{
+			case InitializationOperationType.Remove:
+				box.RemoveAll(lens => lens.Label == step.Label);
+				break;
+			case InitializationOperationType.Insert:
+				{
+					var lens = box.Find(l => l.Label == step.Label);
+					if (lens is null)
+					{
+						lens = new(step.Label);
+						box.Add(lens);
+					}
+
+					lens.FocalLength = step.Parameter;
+					break;
+				}
+			default:
+				throw new InvalidOperationException($"Invalid operation to perform: {step.Operation}.");
+		}
+	}
+
+	public int CalculateFocusingPower()
+	{
+		int totalFocusingPower = 0;
+		for (int boxNumber = 0; boxNumber < _boxes.Length; boxNumber++)
+		{
+			var box = _boxes[boxNumber];
+			if (box is null) continue;
+			for (int slotNumber = 0; slotNumber < box.Count; slotNumber++)
+			{
+				var lens = box[slotNumber];
+				totalFocusingPower += CalculateSingleLensFocusingPower(boxNumber, slotNumber, lens);
+			}
+		}
+
+		return totalFocusingPower;
+	}
+
+	private static int CalculateSingleLensFocusingPower(int boxNumber, int slotNumber, Lens lens)
+	{
+		return (boxNumber + 1) * (slotNumber + 1) * lens.FocalLength;
+	}
+
+	private sealed class Lens(string label)
+	{
+		public string Label { get; } = label;
+		public int FocalLength { get; set; }
+	}
+}