feat: solved day one puzzle

01/Trebuchet/Program.cs

@@ -1,2 +1,121 @@
-// See https://aka.ms/new-console-template for more information
-Console.WriteLine("Hello, World!");
+using System.Text.RegularExpressions;
+
+namespace Trebuchet;
+
+public class Program
+{
+  public async static 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;
+    }
+
+    IPuzzleSolver puzzleSolver = args.Length > 1 && args[1] == "2"
+      ? new PartTwoPuzzleSolver()
+      : new PartOnePuzzleSolver();
+
+    var input = await File.ReadAllLinesAsync(args[0]);
+    var result = puzzleSolver.SumCalibrationValues(input);
+
+    Console.WriteLine($"The sum of all calibration values is {result}.");
+
+    return 0;
+  }
+}
+
+public interface IPuzzleSolver
+{
+  public int SumCalibrationValues(string[] lines);
+  public int GetCalibrationValue(string line);
+}
+
+public class PartOnePuzzleSolver : IPuzzleSolver
+{
+  public int SumCalibrationValues(string[] lines) => lines.Sum(GetCalibrationValue);
+
+  public int GetCalibrationValue(string line)
+  {
+    if (line.Length is 0)
+    {
+      return 0;
+    }
+
+    var numbers = line
+      .Where(char.IsDigit)
+      .Select(char.ToString)
+      .ToList();
+
+    var firstNumber = numbers.First();
+    var lastNumber = numbers.Last();
+
+    return int.Parse(firstNumber + lastNumber);
+  }
+}
+
+public class PartTwoPuzzleSolver : IPuzzleSolver
+{
+  private readonly Dictionary<string, string> _validDigitsAsWords = new() {
+    { "one", "1" },
+    { "two", "2" },
+    { "three", "3" },
+    { "four", "4" },
+    { "five", "5" },
+    { "six", "6" },
+    { "seven", "7" },
+    { "eight", "8" },
+    { "nine", "9" },
+  };
+
+  private bool HasValidDigitAsWord(string word, out string match)
+  {
+    var matchResult = Regex.Match(word, _validDigitsAsWords.Keys.Aggregate((a, b) => @$"{a}|{b}"));
+    match = matchResult.Value;
+    return matchResult.Success;
+  }
+
+  public int SumCalibrationValues(string[] lines) => lines.Sum(GetCalibrationValue);
+
+  public int GetCalibrationValue(string line)
+  {
+    if (line.Length is 0)
+    {
+      return 0;
+    }
+
+    var currentWord = string.Empty;
+    var numbers = new List<string>();
+
+    foreach (var character in line)
+    {
+      currentWord += character;
+
+      if (char.IsDigit(character))
+      {
+        numbers.Add(character.ToString());
+        currentWord = string.Empty;
+      }
+
+      if (HasValidDigitAsWord(currentWord, out var match))
+      {
+        // The last character of the match could be the
+        // first character of the next valid digit as word
+        // so we want to preserve it for the next iteration.
+        numbers.Add(_validDigitsAsWords[match]);
+        currentWord = currentWord.Replace(match[..^1], string.Empty);
+      }
+    }
+
+    var firstNumber = numbers.First();
+    var lastNumber = numbers.Last();
+
+    return int.Parse(firstNumber + lastNumber);
+  }
+}

01/Trebuchet/Trebuchet.csproj

@@ -6,5 +6,4 @@
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
   </PropertyGroup>
-
 </Project>