feat: solve part 1 and part 2 of puzzle 6

06/WaitForIt/Program.cs

@@ -1,2 +1,127 @@
-// See https://aka.ms/new-console-template for more information
-Console.WriteLine("Hello, World!");
+namespace WaitForIt;
+
+public class Program
+{
+  public static async Task<int> Main(string[] args)
+  {
+    if (args.Length is 0)
+    {
+      Console.WriteLine("Please provide a path to the input file.");
+      return -1;
+    }
+
+    if (File.Exists(args[0]) is false)
+    {
+      Console.WriteLine("The provided file does not exist.");
+      return -2;
+    }
+
+    var parser = new PuzzleParser();
+    var input = await File.ReadAllLinesAsync(args[0]);
+
+    long result = args.Length > 1 && args[1] == "part2"
+      ? parser
+        .ParseRace(input)
+        .CalculateNumberOfWaysToWin()
+      : parser.ParseRaces(input)
+        .Select(r => r.CalculateNumberOfWaysToWin())
+        .Aggregate((long)1, (acc, curr) => acc * curr);
+
+    Console.WriteLine($"The product of the margin of errors is {result}.");
+
+    return (int)result;
+  }
+}
+
+/// <summary>
+/// Parses the puzzle input.
+/// </summary>
+public class PuzzleParser
+{
+  private List<long> GetValues(string input) => input
+    .Split(' ', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
+    .Skip(1)
+    .Select(long.Parse)
+    .ToList();
+
+  /// <summary>
+  /// Parses the puzzle input to list of races
+  /// </summary>
+  /// <param name="racesInput">The list of races</param>
+  /// <returns>A list containing instances of <see cref="Race"/>.</returns>
+  public List<Race> ParseRaces(string[] racesInput)
+  {
+    var races = new List<Race>();
+    var durations = GetValues(racesInput[0]);
+    var distances = GetValues(racesInput[1]);
+
+    if (durations.Count != distances.Count)
+    {
+      throw new ArgumentException("The number of times and distances must be equal.");
+    }
+
+    for (int i = 0; i < durations.Count; i++)
+    {
+      races.Add(new Race(durations[i], distances[i]));
+    }
+
+    return races;
+  }
+
+  /// <summary>
+  /// Parses the puzzle input as single race
+  /// </summary>
+  /// <param name="racesInput">The list of races</param>
+  /// <returns>An instance of <see cref="Race"/>.</returns>
+  public Race ParseRace(string[] racesInput)
+  {
+    var duration = string.Join("", GetValues(racesInput[0]).Select(v => v.ToString()));
+    var distance = string.Join("", GetValues(racesInput[1]).Select(v => v.ToString()));
+
+    return new Race(long.Parse(duration), long.Parse(distance));
+  }
+}
+
+/// <summary>
+/// Represents a Race
+/// </summary>
+/// <param name="duration">The duration of the race</param>
+/// <param name="distanceRecord">The distance record</param>
+/// <returns>An instance of <see cref="Race"/>.</returns> 
+public class Race(
+  long duration,
+  long distanceRecord
+)
+{
+  /// <summary>
+  /// Gets the duration of the race
+  /// </summary>
+  public long Duration { get; init; } = duration;
+
+  /// <summary>
+  /// Gets the distance record
+  /// </summary>
+  public long DistanceRecord { get; init; } = distanceRecord;
+
+  /// <summary>
+  /// Calculates the number of ways the race can be won.
+  /// </summary>
+  /// <returns>The number of ways the race can be won.</returns>
+  public long CalculateNumberOfWaysToWin()
+  {
+    var numberOfWaysToWin = 0;
+
+    for (var secsHeld = 0; secsHeld < Duration; secsHeld++)
+    {
+      var speed = 1 * secsHeld;
+      var distance = speed * (Duration - secsHeld);
+
+      if (distance > DistanceRecord)
+      {
+        numberOfWaysToWin++;
+      }
+    }
+
+    return numberOfWaysToWin;
+  }
+}