diff --git a/AdventOfCode.Extensions/AdventOfCode.Extensions.csproj b/AdventOfCode.Extensions/AdventOfCode.Extensions.csproj
new file mode 100644
index 0000000..93bf97d
--- /dev/null
+++ b/AdventOfCode.Extensions/AdventOfCode.Extensions.csproj
@@ -0,0 +1,9 @@
+
+
+
+ net9.0
+ disable
+ enable
+
+
+
diff --git a/AdventOfCode.Extensions/EnumerableExtensions.cs b/AdventOfCode.Extensions/EnumerableExtensions.cs
new file mode 100644
index 0000000..a0d05f0
--- /dev/null
+++ b/AdventOfCode.Extensions/EnumerableExtensions.cs
@@ -0,0 +1,52 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+
+namespace AdventOfCode.Extensions;
+
+public static class EnumerableExtensions
+{
+ public static IEnumerable Combinations(this IEnumerable values, int count)
+ {
+ var pool = values.ToArray();
+ var poolLength = pool.Length;
+ if (count > poolLength)
+ yield break;
+ var indices = Range(0, count).ToArray();
+ yield return GetCombination(indices, pool);
+ while (true)
+ {
+ var validIndex = false;
+ var currentIndex = 0;
+ foreach (var i in Range(0, count).Reverse())
+ {
+ currentIndex = i;
+ if (indices[i] != i + poolLength - count)
+ {
+ validIndex = true;
+ break;
+ }
+ }
+ if(!validIndex)
+ yield break;
+
+ indices[currentIndex] += 1;
+ foreach (var j in Range(currentIndex + 1, count))
+ {
+ Index ix = j - 1;
+ indices[j] = indices[ix] + 1;
+ }
+
+ yield return GetCombination(indices, pool);
+ }
+
+ static TValue[] GetCombination(int[] innerIndices, TValue[] innerPool) =>
+ innerIndices.Select(i => innerPool[i]).ToArray();
+
+ static IEnumerable Range(int start, int end)
+ {
+ for (var i = start; i < end; i++)
+ yield return i;
+ }
+ }
+}
\ No newline at end of file
diff --git a/AdventOfCode.sln b/AdventOfCode.sln
index 1750e5c..9926868 100644
--- a/AdventOfCode.sln
+++ b/AdventOfCode.sln
@@ -10,6 +10,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AoC_2025.Runner", "AoC_2025
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdvenOfCode.Contracts", "AdvenOfCode.Contracts\AdvenOfCode.Contracts.csproj", "{0249A329-D5C1-4699-88BE-A668B362432E}"
EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "AdventOfCode.Extensions", "AdventOfCode.Extensions\AdventOfCode.Extensions.csproj", "{1466A0F6-7C88-47FF-B8F8-FF30368E26DC}"
+EndProject
Global
GlobalSection(SolutionConfigurationPlatforms) = preSolution
Debug|Any CPU = Debug|Any CPU
@@ -32,6 +34,10 @@ Global
{0249A329-D5C1-4699-88BE-A668B362432E}.Debug|Any CPU.Build.0 = Debug|Any CPU
{0249A329-D5C1-4699-88BE-A668B362432E}.Release|Any CPU.ActiveCfg = Release|Any CPU
{0249A329-D5C1-4699-88BE-A668B362432E}.Release|Any CPU.Build.0 = Release|Any CPU
+ {1466A0F6-7C88-47FF-B8F8-FF30368E26DC}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+ {1466A0F6-7C88-47FF-B8F8-FF30368E26DC}.Debug|Any CPU.Build.0 = Debug|Any CPU
+ {1466A0F6-7C88-47FF-B8F8-FF30368E26DC}.Release|Any CPU.ActiveCfg = Release|Any CPU
+ {1466A0F6-7C88-47FF-B8F8-FF30368E26DC}.Release|Any CPU.Build.0 = Release|Any CPU
EndGlobalSection
GlobalSection(NestedProjects) = preSolution
{4F395AE3-DABB-4546-A4D0-5A62425FE168} = {05EBAA1C-B33B-4AFE-8635-A58D7CA509A7}
diff --git a/AoC_2025/AoC_2025.csproj b/AoC_2025/AoC_2025.csproj
index 678a88a..badaa42 100644
--- a/AoC_2025/AoC_2025.csproj
+++ b/AoC_2025/AoC_2025.csproj
@@ -8,6 +8,7 @@
+
diff --git a/AoC_2025/Day08.cs b/AoC_2025/Day08.cs
index 5f1bcef..7f9e54e 100644
--- a/AoC_2025/Day08.cs
+++ b/AoC_2025/Day08.cs
@@ -4,6 +4,7 @@ using System.Data.Common;
using System.IO;
using System.Linq;
using AdvenOfCode.Contracts;
+using AdventOfCode.Extensions;
using Coordinate = (long x, long y, long z);
namespace AoC_2025;
@@ -92,21 +93,11 @@ public class Day08 : IPuzzleSolver
private IEnumerable<(Coordinate boxA, Coordinate boxB)> GetAllCombinationsSortedByDistance(IEnumerable jBoxes)
{
- var combinations = Combinations(jBoxes)
+ var combinations = jBoxes.Combinations(2)
+ .Select(x => (a: x[0], b: x[1]))
.OrderBy(x => GetDistance(x.a, x.b));
return combinations;
}
-
- private IEnumerable<(TValue a, TValue b)> Combinations(IEnumerable values)
- {
- var enumeratedValues = values.Index().ToArray();
- var pairs =
- from a in enumeratedValues
- from b in enumeratedValues
- where a.Index < b.Index
- select (a.Item, b.Item);
- return pairs;
- }
private long MultiplyLargestCircuitLength(List> circuits, int amountMultiply)
{
diff --git a/AoC_2025/Day09.cs b/AoC_2025/Day09.cs
index 4c44c60..4a3e28a 100644
--- a/AoC_2025/Day09.cs
+++ b/AoC_2025/Day09.cs
@@ -4,6 +4,7 @@ using System.Data.Common;
using System.IO;
using System.Linq;
using AdvenOfCode.Contracts;
+using AdventOfCode.Extensions;
using Coordinate = (long x, long y);
using CoordinatePair = (long minX, long minY, long maxX, long maxY);
@@ -54,7 +55,7 @@ public class Day09 : IPuzzleSolver
private IEnumerable GetAllPossibleRectanglesAsPairs(Coordinate[] redTiles)
{
- return Combinations(redTiles).Select(x => AsPair(x.a, x.b));
+ return redTiles.Combinations(2).Select(x => AsPair(x[0], x[1]));
}
private CoordinatePair[] GetBordersAsPairs(Coordinate[] redTiles)
@@ -84,17 +85,6 @@ public class Day09 : IPuzzleSolver
return (Math.Abs(tileA.x - tileB.x) + 1) * (Math.Abs(tileA.y - tileB.y) + 1);
}
- private IEnumerable<(TValue a, TValue b)> Combinations(IEnumerable values)
- {
- var enumeratedValues = values.Index().ToArray();
- var pairs =
- from a in enumeratedValues
- from b in enumeratedValues
- where a.Index < b.Index
- select (a.Item, b.Item);
- return pairs;
- }
-
private IEnumerable<(Coordinate a, Coordinate b)> GetBorders(Coordinate[] tiles)
{
return tiles.Zip([..tiles[1..], tiles[0]], (a, b) => (a, b));
diff --git a/AoC_2025/Day10.cs b/AoC_2025/Day10.cs
index db2714b..9ab5f82 100644
--- a/AoC_2025/Day10.cs
+++ b/AoC_2025/Day10.cs
@@ -6,6 +6,7 @@ using System.Data.Common;
using System.IO;
using System.Linq;
using AdvenOfCode.Contracts;
+using AdventOfCode.Extensions;
using Microsoft.Z3;
namespace AoC_2025;
@@ -214,7 +215,7 @@ public class Day10 : IPuzzleSolver
yield return ([..Enumerable.Repeat(0, patternLength)], 0);
for (var i = 1; i <= buttons.Length; i++)
{
- foreach (var buttonPattern in Combinations(buttons, i))
+ foreach (var buttonPattern in buttons.Combinations(i))
{
var joltageLevels = GetJoltageLevelsForButtonPattern(patternLength, buttonPattern);
yield return (joltageLevels, buttonPattern.Length);
@@ -271,50 +272,6 @@ public class Day10 : IPuzzleSolver
var answer = answerExpression is IntNum number ? number.Int64 : 0;
return answer;
}
-
- private IEnumerable Combinations(IEnumerable values, int count)
- {
- var pool = values.ToArray();
- var poolLength = pool.Length;
- if (count > poolLength)
- yield break;
- var indices = Range(0, count).ToArray();
- yield return GetCombination(indices, pool);
- while (true)
- {
- var validIndex = false;
- var currentIndex = 0;
- foreach (var i in Range(0, count).Reverse())
- {
- currentIndex = i;
- if (indices[i] != i + poolLength - count)
- {
- validIndex = true;
- break;
- }
- }
- if(!validIndex)
- yield break;
-
- indices[currentIndex] += 1;
- foreach (var j in Range(currentIndex + 1, count))
- {
- Index ix = j - 1;
- indices[j] = indices[ix] + 1;
- }
-
- yield return GetCombination(indices, pool);
- }
-
- static TValue[] GetCombination(int[] innerIndices, TValue[] innerPool) =>
- innerIndices.Select(i => innerPool[i]).ToArray();
-
- static IEnumerable Range(int start, int end)
- {
- for (var i = start; i < end; i++)
- yield return i;
- }
- }
}
public class IntArrayEqualityComparer : IEqualityComparer