From 8f642349256848c54db4ad4ee2875a2964ee40d2 Mon Sep 17 00:00:00 2001
From: Sebastian Lindemeier <lindemeier.sebastian@bgetem.de>
Date: Thu, 11 Dec 2025 08:39:25 +0100
Subject: [PATCH] Add Day11 implementation with puzzle-solving logic and tests

---
 AoC_2025.Tests/Day11Test.cs | 48 ++++++++++++++++++++++++
 AoC_2025/Day11.cs           | 74 +++++++++++++++++++++++++++++++++++++
 2 files changed, 122 insertions(+)
 create mode 100644 AoC_2025.Tests/Day11Test.cs
 create mode 100644 AoC_2025/Day11.cs

diff --git a/AoC_2025.Tests/Day11Test.cs b/AoC_2025.Tests/Day11Test.cs
new file mode 100644
index 0000000..93977cb
--- /dev/null
+++ b/AoC_2025.Tests/Day11Test.cs
@@ -0,0 +1,48 @@
+using AdvenOfCode.Contracts;
+
+namespace AoC_2025.Tests;
+
+public class Day11Test
+{
+    private IPuzzleSolver<long> _sut;
+    private static readonly string rootPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
+    private readonly string TestInputPath = @$"{rootPath}\AoC-PuzzleInputs\2025\Test\day11.txt";
+    private readonly string Test2InputPath = @$"{rootPath}\AoC-PuzzleInputs\2025\Test\day11_2.txt";
+    private readonly string ProdInputPath = @$"{rootPath}\AoC-PuzzleInputs\2025\Prod\day11.txt";
+    
+    public Day11Test()
+    {
+        _sut = new Day11();
+    }
+    [Fact]
+    public void Part01_Test_equals_5()
+    {
+        var actual = _sut.SolvePart1(TestInputPath);
+        
+        Assert.Equal(5, actual);
+    }
+    
+    [Fact]
+    public void Part01_Prod_equals_494()
+    {
+        var actual = _sut.SolvePart1(ProdInputPath);
+        
+        Assert.Equal(494, actual);
+    }
+    
+    [Fact]
+    public void Part02_Test2_equals_2()
+    {
+        var actual = _sut.SolvePart2(Test2InputPath);
+        
+        Assert.Equal(2, actual);
+    }
+    
+    [Fact]
+    public void Part02_Prod_equals_296006754704850()
+    {
+        var actual = _sut.SolvePart2(ProdInputPath);
+        
+        Assert.Equal(296006754704850, actual);
+    }
+}
\ No newline at end of file
diff --git a/AoC_2025/Day11.cs b/AoC_2025/Day11.cs
new file mode 100644
index 0000000..2df206e
--- /dev/null
+++ b/AoC_2025/Day11.cs
@@ -0,0 +1,74 @@
+using System;
+using System.Collections.Generic;
+using System.Data;
+using System.Data.Common;
+using System.IO;
+using System.Linq;
+using AdvenOfCode.Contracts;
+
+namespace AoC_2025;
+
+public class Day11 : IPuzzleSolver<long>
+{
+    private Dictionary<string, string[]> ParsePuzzleInput(string path)
+    {
+        var puzzleInput = File.ReadAllLines(path)
+            .Where(line => !string.IsNullOrWhiteSpace(line))
+            .Select(line => line.Split(':', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries))
+            .Select(line => (line[0], line[1].Split(' ', StringSplitOptions.RemoveEmptyEntries)))
+            .ToDictionary();
+            
+        return puzzleInput;
+    }
+
+    public long SolvePart1(string pathToPuzzleInput)
+    {
+        var connections = ParsePuzzleInput(pathToPuzzleInput);
+        var pathsToOut = GetAmountPaths("you", "out", connections, []);
+        return pathsToOut;
+    }
+
+    public long SolvePart2(string pathToPuzzleInput)
+    {
+        var connections = ParsePuzzleInput(pathToPuzzleInput);
+        var pathsToOut = GetAmountPathsThrough("svr", "out", ["dac", "fft"], connections, []);
+        return pathsToOut;
+    }
+
+    private long GetAmountPaths(string from, string to, Dictionary<string, string[]> paths, Dictionary<(string, string), long> memory)
+    {
+        if (from == to) return 1;
+        if (memory.TryGetValue((from, to), out var res)) return res;
+        
+        var totalAmount = 0L;
+        foreach (var path in paths[from])
+        {
+            var amount = GetAmountPaths(path, to, paths, memory);
+            memory[(path, to)] = amount;
+            totalAmount += amount;
+        }
+
+        memory[(from, to)] = totalAmount;
+        return totalAmount;
+    }
+    
+    private long GetAmountPathsThrough(string from, string to, HashSet<string> through, 
+        Dictionary<string, string[]> paths, 
+        Dictionary<(string, string), (long, HashSet<string>)> memory)
+    {
+        through.Remove(from);
+        if (from == to) return through.Count == 0 ? 1 : 0;
+        if (memory.TryGetValue((from, to), out var res) && res.Item2.SetEquals(through)) return res.Item1;
+        
+        var totalAmount = 0L;
+        foreach (var path in paths[from])
+        {
+            var amount = GetAmountPathsThrough(path, to, [..through], paths, memory);
+            memory[(path, to)] = (amount, through);
+            totalAmount += amount;
+        }
+
+        memory[(from, to)] = (totalAmount, through);
+        return totalAmount;
+    }
+}
\ No newline at end of file