From 5e3bb8114068caac0a0685418d0a269770f7a612 Mon Sep 17 00:00:00 2001
From: Buddhism8003 <lindemeier@purelymail.com>
Date: Fri, 30 Jan 2026 21:55:40 +0100
Subject: [PATCH] Added a sliding window extension for IEnumerable

---
 .../EnumerableExtensionsTest.cs               | 40 +++++++++++++++++++
 .../EnumerableExtensions.cs                   | 17 +++++++-
 2 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs b/AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs
index 7f0e479..3d0bcde 100644
--- a/AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs
+++ b/AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs
@@ -102,4 +102,44 @@ public class EnumerableExtensionsTest
 
         Assert.Equal([[1, 2], [1, 3], [2, 1], [2, 3], [3, 1], [3, 2]], actual);
     }
+    
+    [Fact]
+    public void SlidingWindowOver_none_1_equals_none()
+    {
+        int[] data = [];
+        
+        var actual = data.SlidingWindow(1).ToArray();
+        
+        Assert.Equal([], actual);
+    }
+    
+    [Fact]
+    public void SlidingWindowOver_1_1_equals_1()
+    {
+        int[] data = [1];
+        
+        var actual = data.SlidingWindow(1).ToArray();
+        
+        Assert.Equal([[1]], actual);
+    }
+    
+    [Fact]
+    public void SlidingWindowOver_1234_2_equals_1_12_23_34()
+    {
+        int[] data = [1, 2, 3, 4];
+        
+        var actual = data.SlidingWindow(2).ToArray();
+        
+        Assert.Equal([[1], [1, 2], [2, 3], [3, 4]], actual);
+    }
+    
+    [Fact]
+    public void SlidingWindowOver_1234_3_equals_1_12_123_234()
+    {
+        int[] data = [1, 2, 3, 4];
+        
+        var actual = data.SlidingWindow(3).ToArray();
+        
+        Assert.Equal([[1], [1, 2], [1, 2, 3], [2, 3, 4]], actual);
+    }
 }
\ No newline at end of file
diff --git a/AdventOfCode.Extensions/EnumerableExtensions.cs b/AdventOfCode.Extensions/EnumerableExtensions.cs
index 20c5efd..15da20b 100644
--- a/AdventOfCode.Extensions/EnumerableExtensions.cs
+++ b/AdventOfCode.Extensions/EnumerableExtensions.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Numerics;
 
 namespace AdventOfCode.Extensions;
 
@@ -144,6 +145,18 @@ public static class EnumerableExtensions
         }
     }
     
-    private static TValue[] GetCombination<TValue>(int[] innerIndices, TValue[] innerPool) => 
-        innerIndices.Select(i => innerPool[i]).ToArray();
+    private static TValue[] GetCombination<TValue>(int[] indices, TValue[] values) => 
+        indices.Select(i => values[i]).ToArray();
+
+    public static IEnumerable<TValue[]> SlidingWindow<TValue>(this IEnumerable<TValue> values, int count)
+    {
+        var queue = new Queue<TValue>(count);
+        foreach (var value in values)
+        {
+            queue.Enqueue(value);
+            if(queue.Count > count)
+                queue.Dequeue();
+            yield return queue.ToArray();
+        }
+    }
 }
\ No newline at end of file