feat: solve part 1

15/LensLibrary/Program.cs

@@ -1,9 +1,53 @@
-namespace LensLibrary;
+using System.Diagnostics;
+
+namespace LensLibrary;
 
 public class Program
 {
   public static async Task<int> Main(string[] args)
   {
-    return await Task.FromResult(0);
+    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 input = await File.ReadAllTextAsync(args[0]);
+    var steps = input.Split(
+      ',',
+      StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries
+    );
+
+    var stopwatch = new Stopwatch();
+    stopwatch.Start();
+
+    var total = 0;
+
+    foreach (var step in steps)
+    {
+      var stepValue = 0;
+
+      foreach (var character in step)
+      {
+        var ascii = (int)character;
+        stepValue += ascii;
+        stepValue *= 17;
+        stepValue %= 256;
+      }
+
+      total += stepValue;
+    }
+
+    stopwatch.Stop();
+
+    Console.WriteLine($"The total is {total}. ({stopwatch.ElapsedMilliseconds}ms)");
+
+    return total;
   }
 }