Day 23

aoc/src/dev/ctsk/aoc/Main.scala

@@ -24,7 +24,8 @@ val solvers = Map[Int, Solver](
   19 -> Day19,
   20 -> Day20,
   21 -> Day21,
-  22 -> Day22
+  22 -> Day22,
+  23 -> Day23
 )
 
 def runSolver(solver: Solver, input: os.Path): Unit =
@@ -34,16 +35,14 @@ def runSolver(solver: Solver, input: os.Path): Unit =
       println(solution.p1)
       println(solution.p2)
     case None =>
-      println(f"==============================================")
-      println(f"Day ${solver.day}%02d ---------------------------------------")
-      println(f"Prep ${timings.prep}%38s μs")
-      println(f"Part 1 ${solution.p1}%20s ${timings.p1}%15s μs")
-      println(f"Part 2 ${solution.p2}%20s ${timings.p2}%15s μs")
-      println(f"----------------------------------------------")
-
-      println(f"Total ${timings.total}%37s μs")
-
-      println(f"==============================================")
+      println(f"=============================================================")
+      println(f"Day ${solver.day}%02d ------------------------------------------------------")
+      println(f"Prep ${timings.prep}%53s μs")
+      println(f"Part 1 ${solution.p1}%40s ${timings.p1}%10s μs")
+      println(f"Part 2 ${solution.p2}%40s ${timings.p2}%10s μs")
+      println(f"-------------------------------------------------------------")
+      println(f"Total ${timings.total}%52s μs")
+      println(f"=============================================================")
 
 @main def main(day: String, input: String): Unit =
   val num = """(\d+)""".r

aoc/src/dev/ctsk/aoc/days/Day23.scala

@@ -0,0 +1,59 @@
+package dev.ctsk.aoc.days
+
+import dev.ctsk.aoc.*
+
+object Day23 extends Solver(23):
+  override def run(input: os.ReadablePath): (Timings, Solution) =
+    val edge = "([^-]*)-([^-]*)".r
+
+    def id(s: String): Int = (s(0) - 'a') * 26 + (s(1) - 'a')
+
+    val (pre_time, graph) = timed {
+      os.read
+        .lines(input)
+        .flatMap { case edge(from, to) => Seq((from, to), (to, from)) }
+        .groupMap(_._1)(_._2)
+        .view
+        .mapValues(_.toSet)
+        .toMap
+    }
+
+    val (p1_time, triangles) = timed {
+      (for
+        (u, uOut) <- graph
+        v <- uOut
+        w <- graph(v).intersect(uOut)
+        if Seq(u(0), v(0), w(0)).contains('t')
+      yield Set(u, v, w)).toSet.size
+    }
+
+    type Nodes = Set[String]
+    def cliques(clique: Nodes, cand_ : Nodes, excl_ : Nodes): Set[Nodes] =
+      if cand_.isEmpty && excl_.isEmpty then return Set(clique)
+      if cand_.isEmpty then return Set.empty
+      val pivot = cand_.maxBy(graph(_).size)
+
+      var candidates = cand_
+      var excluded = excl_
+      var acc = Set.empty[Set[String]]
+
+      for v <- cand_ -- graph(pivot)
+      do
+        acc ++= cliques(clique + v, candidates & graph(v), excluded & graph(v))
+        candidates = candidates - v
+        excluded = excluded + v
+
+      acc
+
+    val (p2_time, password) = timed {
+      cliques(Set.empty, graph.keySet, Set.empty)
+        .maxBy(_.size)
+        .toArray
+        .sorted
+        .mkString(",")
+    }
+
+    (
+      Timings(pre_time, p1_time, p2_time),
+      Solution(Int.box(triangles), password)
+    )

data/23.ans

@@ -0,0 +1,2 @@
+1064
+aq,cc,ea,gc,jo,od,pa,rg,rv,ub,ul,vr,yy