From 31caf429caca9a94d65b4c3d5f9ff3b477c7fd09 Mon Sep 17 00:00:00 2001
From: Sebastian Lindemeier <lindemeier.sebastian@bgetem.de>
Date: Fri, 5 Dec 2025 09:04:27 +0100
Subject: [PATCH] Refactor Day04 to use Index() extension method

---
 AoC_2025.Tests/Day05Test.cs | 18 +++++++++++++++++-
 AoC_2025/Day04.cs           |  9 +++++----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/AoC_2025.Tests/Day05Test.cs b/AoC_2025.Tests/Day05Test.cs
index 80d9f28..f96ecd7 100644
--- a/AoC_2025.Tests/Day05Test.cs
+++ b/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);
+    }
 }
\ No newline at end of file
diff --git a/AoC_2025/Day04.cs b/AoC_2025/Day04.cs
index 91b34b2..77f54a2 100644
--- a/AoC_2025/Day04.cs
+++ b/AoC_2025/Day04.cs
@@ -55,16 +55,17 @@ public class Day04 : IPuzzleSolver<long>
     private HashSet<Coordinate> GetRollCoordinates(IEnumerable<string> paperrollGrid)
     {
         var coordinates = paperrollGrid
-            .SelectMany((gridLine, xIndex) => GetCoordinates(gridLine, xIndex))
+            .Index()
+            .SelectMany(indexedLine => GetCoordinates(indexedLine.Item, indexedLine.Index))
             .ToHashSet();
         return coordinates;
     }
 
     private IEnumerable<Coordinate> GetCoordinates(string gridLine, int xIndex)
     {
-        var indexedCharacters = gridLine.Select((character, yIndex) => (character, yIndex));
-        var validRolls = indexedCharacters.Where(tuple => tuple.character == '@');
-        var rollCoordinates = validRolls.Select(tuple => (xIndex, tuple.yIndex));
+        var indexedCharacters = gridLine.Index();
+        var validRolls = indexedCharacters.Where(tuple => tuple.Item == '@');
+        var rollCoordinates = validRolls.Select(tuple => (xIndex, tuple.Index));
         return rollCoordinates;
     }