Refactor Day04 to use Index() extension method

AoC_2025.Tests/Day05Test.cs

@@ -4,7 +4,7 @@ namespace AoC_2025.Tests;
 
 public class Day05Test
 {
-    private readonly IPuzzleSolver<long> _sut;
+    private readonly Day05 _sut;
     private static readonly string rootPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
     private readonly string TestInputPath = @$"{rootPath}\AoC-PuzzleInputs\2025\Test\day05.txt";
     private readonly string ProdInputPath = @$"{rootPath}\AoC-PuzzleInputs\2025\Prod\day05.txt";
@@ -44,4 +44,20 @@ public class Day05Test
         
         Assert.Equal(369761800782619, actual);
     }
+    
+    [Fact]
+    public void Part02Again_Test_equals_14()
+    {
+        var actual = _sut.SolvePart2Again(TestInputPath);
+        
+        Assert.Equal(14, actual);
+    }
+    
+    [Fact]
+    public void Part02Again_Prod_equals_369761800782619()
+    {
+        var actual = _sut.SolvePart2Again(ProdInputPath);
+        
+        Assert.Equal(369761800782619, actual);
+    }
 }