1 files changed, 73 insertions, 0 deletions
diff --git a/2024/aoc2024-d23.py b/2024/aoc2024-d23.py
new file mode 100644
index 0000000..ca87fb3
--- /dev/null
+++ b/2024/aoc2024-d23.py
@@ -0,0 +1,73 @@
+#advent of code 2024
+#day 23
+#this is rewritten to adapt for part 2. All possible sets of computers 
+#are searched for recursively (with FindNetwork function) 
+#and stored in subnetworks set. Then it iterates over all elements of 
+#subnetworks set. If the element has 3 computers, then it iterates over
+#all computers in the set. If at least one computer starts with "t",
+#it is counted towards part 1. We keep track of the longest set of 
+#computers and update part2 variable when it changes. 
+#The way FindNetwork works is that it takes a name of PC and a set of previously
+#visited computers that are all iterconnected. Then the given PC is added
+#to the set, the set is sorted (to avoid duplicates) and added to 
+#subnetworks set. It iterates over all computers connected to PC from argument 
+#according to Connections dictionary. If the computer is already in 
+#the cluster, it is skipped. Then, we nest another loop to check if the 
+#connections of the computer match the computers in the cluster.
+#if not, it's skipped. if yes, it call the FindNetwork function again 
+#with the computer and updated cluster (NextCluster) as arguments.
+#infinite loop is prevented while checking whether or not the computer
+#is already in the cluster. Runtime is sped up due to discarding already
+#visited clusters accoroding to subnetworks set.
+#the password for part2 is just a string of computer names separated with commas
+#similar to previous day
+#I think the correct term is "ring" or "topology" but that's completely irrelevant
+#for the puzzle
+
+Connections = {};
+f = open("23.in","r");
+for l in f:
+	PC1, PC2 = l.strip().split("-");
+	if PC1 not in Connections: Connections[PC1] = set();
+	if PC2 not in Connections: Connections[PC2] = set();
+	Connections[PC1].add(PC2);
+	Connections[PC2].add(PC1);
+f.close();
+
+subnetworks = set();
+
+def FindNetwork(PC,Cluster):
+	NextCluster = Cluster.copy();
+	NextCluster.add(PC);
+	NextCluster = sorted(NextCluster);
+	if tuple(NextCluster) in subnetworks: return;
+	subnetworks.add(tuple(NextCluster));
+	for NextPC in Connections[PC]:
+		ok = True;
+		if NextPC in Cluster: continue;
+		for OtherPCs in NextCluster:
+			if OtherPCs not in Connections[NextPC]: ok = False;
+		if not ok: continue;
+		FindNetwork(NextPC, set(NextCluster));
+
+
+for i,computer in enumerate(Connections):
+	print(i, "/", len(Connections));
+	FindNetwork(computer,set());
+
+part1 = 0;
+part2 = None;
+LargestNetworkSize = 0;
+for subnet in subnetworks:
+	SubnetSize = len(subnet)
+	if SubnetSize == 3: 
+		for computer in subnet:
+			if computer[0] == "t": 
+				part1 += 1;
+				break;
+	LargestNetworkSize = max(LargestNetworkSize,SubnetSize);
+	if LargestNetworkSize == SubnetSize: part2 = subnet;
+
+part2 = ",".join(part2);
+print("part 1 =",part1);
+print("part 2 =",part2);