solve second puzzle correctly

rpgrca · Dec 24, 2024 · 5a65c14 · 5a65c14
1 parent 6c3f6b0
commit 5a65c14
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Showing 2 changed files with 34 additions and 5 deletions.
diff --git a/2024/Day23/Day23.Logic/LanParty.cs b/2024/Day23/Day23.Logic/LanParty.cs
@@ -1,6 +1,4 @@
 
-using System.Net.Sockets;
-
 namespace Day23.Logic;
 
 public class LanParty
@@ -32,7 +30,6 @@ public List<string> FindPartiesOf(int size)
         var result = new List<string>();
         foreach (var computer in _connections)
         {
-            if (computer.Value.Count >= size)
             {
                 foreach (var other in computer.Value)
                 {
@@ -70,4 +67,36 @@ public int FindNetworksWithComputerStartingWith(int size, char initialLetter)
 
         return result.Distinct().Count();
     }
+
+    public string CalculateLargestNetworkParty() =>
+        string.Join(',', FindLargestClique().OrderByDescending(c => c.Count).First().Order());
+
+    public List<List<string>> FindLargestClique()
+    {
+        var computers = _connections.Keys.ToList();
+        var allCliques = new List<List<string>>();
+        ApplyBronKerboschAlgorithm(new List<string>(), computers, new List<string>(), _connections, allCliques);
+        return allCliques;
+    }
+
+    private void ApplyBronKerboschAlgorithm(List<string> R, List<string> P, List<string> X, Dictionary<string, List<string>> graph, List<List<string>> allCliques)
+    {
+        if (! (P.Any() || X.Any()))
+        {
+            allCliques.Add(new List<string>(R));
+            return;
+        }
+
+        var pivot = P.Concat(X).First();
+        var nonNeighbors = P.Except(graph[pivot]).ToList();
+
+        foreach (var node in nonNeighbors)
+        {
+            R.Add(node);
+            ApplyBronKerboschAlgorithm(R, P.Intersect(graph[node]).ToList(), X.Intersect(graph[node]).ToList(), graph, allCliques);
+            R.Remove(node);
+            P.Remove(node);
+            X.Add(node);
+        }
+    }
 }
diff --git a/2024/Day23/Day23.UnitTests/LanPartyMust.cs b/2024/Day23/Day23.UnitTests/LanPartyMust.cs
@@ -46,7 +46,7 @@ public void SolveFirstSampleCorrectly()
     public void SolveFirstPuzzleCorrectly()
     {
         var sut = new LanParty(PUZZLE_INPUT);
-        var result = sut.FindNetworksWithComputerStartingWith(3, 't');
-        Assert.Equal(1175, result);
+        var result = sut.CalculateLargestNetworkParty();
+        Assert.Equal("bw,dr,du,ha,mm,ov,pj,qh,tz,uv,vq,wq,xw", result);
     }
 }