Added a sliding window extension for IEnumerable

AdventOfCode.Extensions.Tests/EnumerableExtensionsTest.cs

@@ -4,13 +4,13 @@ namespace AdventOfCode.Extensions.Tests;
 public class EnumerableExtensionsTest
 {
     [Fact]
-    public void Combinations_12_2_equals_12_21()
+    public void Combinations_12_2_equals_12()
     {
         int[] data = [1, 2];
 
         var actual = data.Combinations(2).ToArray();
         
-        Assert.Contains([1, 2], actual);
+        Assert.Equal([[1, 2]], actual);
     }
     
     [Fact]
@@ -20,9 +20,7 @@ public class EnumerableExtensionsTest
 
         var actual = data.Combinations(2).ToArray();
 
-        Assert.Contains([1, 2], actual);
-        Assert.Contains([1, 3], actual);
-        Assert.Contains([2, 3], actual);
+        Assert.Equal([[1, 2], [1, 3], [2, 3]], actual);
     }
     
     [Fact]
@@ -32,6 +30,116 @@ public class EnumerableExtensionsTest
 
         var actual = data.Combinations(3).ToArray();
         
-        Assert.Contains([1, 2, 3], actual);
+        Assert.Equal([[1, 2, 3]], actual);
+    }
+    
+    [Fact]
+    public void Combinations_repeated_12_2_equals_11_12_22()
+    {
+        int[] data = [1, 2];
+
+        var actual = data.CombinationsWithRepeats(2).ToArray();
+        
+        Assert.Equal([[1, 1], [1, 2], [2, 2]], actual);
+    }
+    
+    [Fact]
+    public void Combinations_repeated_123_2_equals_11_12_13_22_23_33()
+    {
+        int[] data = [1, 2, 3];
+
+        var actual = data.CombinationsWithRepeats(2).ToArray();
+
+        Assert.Equal([[1, 1], [1, 2], [1, 3], [2, 2], [2, 3], [3, 3]], actual);
+    }
+    
+    [Fact]
+    public void Combinations_repeated_123_3_equals_many()
+    {
+        int[] data = [1, 2, 3];
+
+        var actual = data.CombinationsWithRepeats(3).ToArray();
+        
+        Assert.Equal([[1, 1, 1], [1, 1, 2], [1, 1, 3], [1, 2, 2], [1, 2, 3], [1, 3, 3], [2, 2, 2], [2, 2, 3], [2, 3, 3], [3, 3, 3]], actual);
+    }
+    
+    [Fact]
+    public void Permutations_repeated_12_2_equals_11_12_21_22()
+    {
+        int[] data = [1, 2];
+
+        var actual = data.PermutationsWithRepeats(2).ToArray();
+        
+        Assert.Equal([[1, 1], [1, 2], [2, 1], [2, 2]], actual);
+    }
+    
+    [Fact]
+    public void Permutations_12_2_equals_12_21()
+    {
+        int[] data = [1, 2];
+
+        var actual = data.Permutations(2).ToArray();
+
+        Assert.Equal([[1, 2], [2, 1]], actual);
+    }
+    
+    [Fact]
+    public void Permutations_repeated_123_2_equals_11_12_13_21_22_23_31_32_33()
+    {
+        int[] data = [1, 2, 3];
+
+        var actual = data.PermutationsWithRepeats(2).ToArray();
+
+        Assert.Equal([[1, 1], [1, 2], [1, 3], [2, 1], [2, 2], [2, 3], [3, 1], [3, 2], [3, 3]], actual);
+    }
+    
+    [Fact]
+    public void Permutations_123_2_equals_12_13_21_23_31_32()
+    {
+        int[] data = [1, 2, 3];
+
+        var actual = data.Permutations(2).ToArray();
+
+        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);
     }
 }

AdventOfCode.Extensions/EnumerableExtensions.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Numerics;
 
 namespace AdventOfCode.Extensions;
 
@@ -12,41 +13,150 @@ public static class EnumerableExtensions
         var poolLength = pool.Length;
         if (count > poolLength)
             yield break;
-        var indices = Range(0, count).ToArray();
+        int[] indices = [..Enumerable.Range(0, count)];
         yield return GetCombination(indices, pool);
         while (true)
         {
-            var validIndex = false;
-            var currentIndex = 0;
-            for(var i = count - 1; i >= 0; i--)
+            var idx = count - 1;
+            for(;idx >= 0; --idx)
             {
-                currentIndex = i;
-                if (indices[i] != i + poolLength - count)
-                {
-                    validIndex = true;
+                var maxPossibleIndex = idx + poolLength - count;
+                var isIndexBelowMax = indices[idx] != maxPossibleIndex;
+                if (isIndexBelowMax) 
                     break;
-                }
             }
-            if(!validIndex)
+            if(idx < 0)
                 yield break;
             
-            indices[currentIndex] += 1;
-            foreach (var j in Range(currentIndex + 1, count))
+            indices[idx] += 1;
+            for (var j = idx + 1; j < indices.Length; j++)
             {
-                Index ix = j - 1;
-                indices[j] = indices[ix] + 1;
+                indices[j] = indices[j - 1] + 1;
             }
 
             yield return GetCombination(indices, pool);
         }
+    }
     
-        static TValue[] GetCombination(int[] innerIndices, TValue[] innerPool) => 
-            innerIndices.Select(i => innerPool[i]).ToArray();
-
-        static IEnumerable<int> Range(int start, int end)
+    public static IEnumerable<TValue[]> CombinationsWithRepeats<TValue>(this IEnumerable<TValue> values, int count)
+    {
+        var pool = values.ToArray();
+        var poolLength = pool.Length;
+        if (count > poolLength)
+            yield break;
+        int[] indices = [..Enumerable.Repeat(0, count)];
+        yield return GetCombination(indices, pool);
+        while (true)
         {
-            for (var i = start; i < end; i++)
-                yield return i;
+            var idx = count - 1;
+            for(;idx >= 0; --idx)
+            {
+                var maxPossibleIndex = poolLength - 1;
+                var isIndexBelowMax = indices[idx] != maxPossibleIndex;
+                if (isIndexBelowMax) 
+                    break;
+            }
+            if(idx < 0)
+                yield break;
+            
+            var num = indices[idx];
+            for (var j = idx; j < indices.Length; j++)
+            {
+                indices[j] = num + 1;
+            }
+
+            yield return GetCombination(indices, pool);
+        }
+    }
+    
+    public static IEnumerable<TValue[]> PermutationsWithRepeats<TValue>(this IEnumerable<TValue> values, int count)
+    {
+        var pool = values.ToArray();
+        if (count > pool.Length)
+            yield break;
+        var indices = Enumerable.Repeat(0, count).ToArray();
+        yield return GetCombination(indices, pool);
+        while (true)
+        {
+            var idx = count - 1;
+            for(;idx > 0; --idx)
+            {
+                var isIndexBelowMax = indices[idx] != idx + pool.Length - count;
+                if (isIndexBelowMax) 
+                    break;
+            }
+            if(indices.All(i => i >= pool.Length - 1))
+                yield break;
+            indices[idx] += 1;
+            for (var j = idx + 1; j < count; j++)
+            {
+                indices[j] = 0;
+            }
+
+            yield return GetCombination(indices, pool);
+        }
+    }
+    
+    public static IEnumerable<TValue[]> Permutations<TValue>(this IEnumerable<TValue> values, int count)
+    {
+        var pool = values.ToArray();
+        var poolLength = pool.Length;
+        if (count > poolLength)
+            yield break;
+        var indices = Enumerable.Range(0, poolLength).ToArray();
+        var cycles = Enumerable.Range(0, poolLength + 1)
+            .Skip(poolLength - count + 1)
+            .Reverse()
+            .ToArray();
+        yield return GetCombination(indices[..count], pool);
+        var notDone = true;
+        while (notDone)
+        {
+            notDone = false;
+            for (var i = count - 1; i >= 0; i--)
+            {
+                cycles[i] -= 1;
+                if (cycles[i] == 0)
+                {
+                    RotateIndices(indices, i);
+                    cycles[i] = poolLength - i;
+                }
+                else
+                {
+                    var j = cycles[i];
+                    (indices[i], indices[^j]) = (indices[^j], indices[i]);
+                    yield return GetCombination(indices[..count], pool);
+                    notDone = true;
+                    break;
+                }
+            }
+        }
+
+        yield break;
+
+        static void RotateIndices(int[] indices, int from)
+        {
+            var tmp = indices[from];
+            for (var j = from; j < indices.Length - 1; j++)
+            {
+                indices[j] = indices[j + 1];
+            }
+            indices[^1] = tmp;
+        }
+    }
+    
+    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();
         }
     }
 }

AdventOfCode.HelperClasses/Coordinate.cs

@@ -2,6 +2,12 @@
 
 public record Coordinate(long X, long Y)
 {
+    public long GetManhattanDistance(Coordinate other) =>
+        GetManhattanDistance(this, other);
+
+    public static long GetManhattanDistance(Coordinate a, Coordinate b) =>
+        Math.Abs(a.X - b.X) + Math.Abs(a.Y - b.Y);
+    
     public double GetEuclidianDistance(Coordinate other) =>
         GetEuclidianDistance(this, other);
 
@@ -10,10 +16,22 @@ public record Coordinate(long X, long Y)
     
     public static Coordinate operator +(Coordinate left, Coordinate right) => 
         new(left.X + right.X, left.Y + right.Y);
+    
+    public static Coordinate operator -(Coordinate left, Coordinate right) => 
+        new(left.X - right.X, left.Y - right.Y);
+    
+    public static Coordinate operator *(Coordinate coord, int amount) => 
+        new(coord.X * amount, coord.Y * amount);
 }
 
 public record Coordinate3d(long X, long Y, long Z)
 {
+    public long GetManhattanDistance(Coordinate3d other) =>
+        GetManhattanDistance(this, other);
+
+    public static long GetManhattanDistance(Coordinate3d a, Coordinate3d b) =>
+        Math.Abs(a.X - b.X) + Math.Abs(a.Y - b.Y) + Math.Abs(a.Z - b.Z);
+    
     public double GetEuclidianDistance(Coordinate3d other) =>
         GetEuclidianDistance(this, other);
 
@@ -22,4 +40,44 @@ public record Coordinate3d(long X, long Y, long Z)
     
     public static Coordinate3d operator +(Coordinate3d left, Coordinate3d right) => 
         new(left.X + right.X, left.Y + right.Y, left.Z + right.Z);
+    
+    public static Coordinate3d operator -(Coordinate3d left, Coordinate3d right) => 
+        new(left.X - right.X, left.Y - right.Y, left.Z - right.Z);
+    
+    public static Coordinate3d operator *(Coordinate3d coord, int amount) => 
+        new(coord.X * amount, coord.Y * amount, coord.Z * amount);
 }
+
+public record CoordinateNd(long[] Axes)
+{
+    public long GetManhattanDistance(CoordinateNd other) =>
+        GetManhattanDistance(this, other);
+
+    public static long GetManhattanDistance(CoordinateNd a, CoordinateNd b) =>
+        a.Axes.Length == b.Axes.Length 
+            ? a.Axes.Zip(b.Axes, (ax, bx) => Math.Abs(ax - bx)).Sum()
+            : throw new DimensionMismatchException();
+    
+    public double GetEuclidianDistance(CoordinateNd other) =>
+        GetEuclidianDistance(this, other);
+
+    public static double GetEuclidianDistance(CoordinateNd a, CoordinateNd b) =>
+        a.Axes.Length == b.Axes.Length 
+            ? Math.Sqrt(a.Axes.Zip(b.Axes, (ax, bx) => (ax - bx) * (ax - bx)).Sum())
+            : throw new DimensionMismatchException();
+    
+    public static CoordinateNd operator +(CoordinateNd left, CoordinateNd right) => 
+        left.Axes.Length == right.Axes.Length 
+            ? new CoordinateNd([..left.Axes.Zip(right.Axes, (l, r) => l + r)])
+            : throw new DimensionMismatchException();
+    
+    public static CoordinateNd operator -(CoordinateNd left, CoordinateNd right) => 
+        left.Axes.Length == right.Axes.Length 
+            ? new CoordinateNd([..left.Axes.Zip(right.Axes, (l, r) => l - r)])
+            : throw new DimensionMismatchException();
+
+    public static CoordinateNd operator *(CoordinateNd coord, int amount) =>
+        new CoordinateNd([..coord.Axes.Select(a => a * amount)]);
+}
+
+public class DimensionMismatchException : Exception {}

AoC_2025/Day10.cs

@@ -23,9 +23,8 @@ public class Day10 : IPuzzleSolver<long>
             .ToArray();
         var lamps = puzzleInput
             .Select(input => input.lamps)
-            .Select(lamps => lamps.Index())
-            .Select(ixlamps =>
-                ixlamps.Select(ixlamp => ixlamp.Item == '#').ToArray())
+            .Select(lamps =>
+                lamps.Select(lamp => lamp == '#').ToArray())
             .ToArray();
         var buttons = puzzleInput
             .Select(input => input.buttons)