completed day four part 1

AdventOfCode2025/AdventOfCode2025.csproj

@@ -24,6 +24,10 @@
       <Content Include="Input\DayThree.txt">
         <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
       </Content>
+      <None Remove="Input\DayFour.txt" />
+      <Content Include="Input\DayFour.txt">
+        <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+      </Content>
     </ItemGroup>
 
 </Project>

AdventOfCode2025/PrintingDepartment.cs

@@ -1,9 +1,44 @@
-namespace AdventOfCode2025;
+using AdventOfCode2025.Utils;
+
+namespace AdventOfCode2025;
 
 public class PrintingDepartment : IAdventSolution
 {
+    private readonly HashSet<Coordinate> _existingRolls = new();
     public AdventSolution Solve(string input)
     {
-        throw new NotImplementedException();
+        var map = input.SplitLines();
+        for (var i = 0; i < map.Length; i++)
+        {
+            for (var j = 0; j < map[i].Length; j++)
+            {
+                if(map[i][j] != '.')
+                    _existingRolls.Add(new Coordinate(j, i));
+            }
+        }
+
+        var accessible = 0;
+        foreach (var c in _existingRolls)
+        {
+            if(IsAccessible(c)) accessible++;
+        }
+        
+        return new AdventSolution(accessible.ToString(), null);
+    }
+
+    private readonly Coordinate[] _directions =
+    [
+        new(-1, -1), new( 0, -1), new( 1, -1),
+        new(-1,  0),              new( 1,  0),
+        new(-1,  1), new( 0,  1), new( 1,  1)
+    ];
+    private bool IsAccessible(Coordinate position)
+    {
+        var neighbors = 0;
+        foreach (var dir in _directions)
+        {
+            if(_existingRolls.Contains(position + dir)) neighbors++;
+        }
+        return neighbors < 4;
     }
 }

AdventOfCode2025/Program.cs

@@ -11,5 +11,5 @@ AdventSolver<GiftShop>.Solve(dayTwoInput, 2, "Gift Shop");
 var dayThreeInput = await File.ReadAllTextAsync("./Input/DayThree.txt");
 AdventSolver<Lobby>.Solve(dayThreeInput, 3, "Lobby");
 
-var dayFourInput = await File.ReadAllTextAsync("./Input/Test.txt");
+var dayFourInput = await File.ReadAllTextAsync("./Input/DayFour.txt");
 AdventSolver<PrintingDepartment>.Solve(dayFourInput, 4, "Printing Department");