Extract IntArrayEqualityComparer to new AdventOfCode.HelperClasses project and refactor solution to use the shared class

AdventOfCode.HelperClasses/AdventOfCode.HelperClasses.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <TargetFramework>net9.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+</Project>

AdventOfCode.HelperClasses/IntArrayEqualityComparer.cs

@@ -0,0 +1,24 @@
+namespace AdventOfCode.HelperClasses;
+
+public class IntArrayEqualityComparer : IEqualityComparer<int[]>
+{
+    public bool Equals(int[]? x, int[]? y)
+    {
+        if (x is null || y is null || x.Length != y.Length) return false;
+
+        return !x.Where((t, i) => t != y[i]).Any();
+    }
+
+    public int GetHashCode(int[] obj)
+    {
+        var result = 17;
+        foreach (var t in obj)
+        {
+            unchecked
+            {
+                result = result * 23 + t;
+            }
+        }
+        return result;
+    }
+}