2024 day 23.

src/holt59/aoc/2024/day23.py

@@ -1,7 +1,36 @@
+from collections import defaultdict
 from typing import Any, Iterator
 
 from ..base import BaseSolver
+from ..tools.graphs import iter_max_cliques
 
 
 class Solver(BaseSolver):
-    def solve(self, input: str) -> Iterator[Any]: ...
+    def solve(self, input: str) -> Iterator[Any]:
+        connections: dict[str, set[str]] = defaultdict(set)
+        for row in input.splitlines():
+            src, dst = row.split("-")
+            connections[src].add(dst)
+            connections[dst].add(src)
+
+        if self.files:
+            content = "graph G {\n"
+            for row in input.splitlines():
+                src, dst = row.split("-")
+                content += f"{src} -- {dst}\n"
+            content += "}"
+            self.files.create("graph.dot", content.encode(), False)
+
+        cliques: set[frozenset[str]] = set()
+
+        for node1, neighbors in connections.items():
+            for node2 in neighbors:
+                for node3 in connections[node2].intersection(neighbors):
+                    cliques.add(frozenset({node1, node2, node3}))
+
+        self.logger.info(f"found {len(cliques)} cliques of size 3")
+        yield sum(any(node.startswith("t") for node in clique) for clique in cliques)
+
+        # clique = max(nx.algorithms.clique.find_cliques(G), key=len)
+        clique = max(iter_max_cliques(connections), key=len)
+        yield ",".join(sorted(clique))