day 8 puzzle 2 (naive and not optimized)

src/day8/Puzzle2.scala

@@ -0,0 +1,56 @@
+package day8
+
+import scala.collection.mutable
+import scala.io.{BufferedSource, Source}
+import scala.util.matching.Regex
+import scala.util.matching.Regex.Match
+
+object Puzzle2 {
+  var rule: Array[Int] = Array.empty
+  val nodes: mutable.Map[String, Node] = new mutable.HashMap()
+  var ghosts: Array[Ghost] = Array.empty
+  def loadInput(path: String): Unit = {
+    val source: BufferedSource = Source.fromFile(path)
+    val lines: String = source.getLines().mkString("\n")
+    val parts: Array[String] = lines.split("\n\n")
+
+    rule = parts(0).map(c => "LR".indexOf(c)).toArray
+    val regexp: Regex = new Regex("([A-Z]{3}) = \\(([A-Z]{3}), ([A-Z]{3})\\)")
+    for (line: String <- parts(1).split("\n")) {
+      val matches: Match = regexp.findFirstMatchIn(line).get
+      val id: String = matches.group(1)
+      val left: String = matches.group(2)
+      val right: String = matches.group(3)
+      nodes(id) = new Node(id, Array(left, right))
+    }
+
+    source.close()
+  }
+
+  def solve(path: String): Long = {
+    loadInput(path)
+
+    ghosts = nodes.keys.filter(k => k.last == 'A').map(k => new Ghost(k)).toArray
+
+    val ghostDists: mutable.Map[Ghost, Long] = new mutable.HashMap()
+    for (ghost: Ghost <- ghosts) {
+      println(s"Ghost from ${ghost.startId}")
+      ghost.computePath(nodes, rule)
+      ghostDists(ghost) = ghost.next()
+    }
+
+    while (ghostDists.values.toArray.distinct.length != 1) {
+      val minimum: (Ghost, Long) = ghostDists.toArray.minBy(_._2)
+      ghostDists(minimum._1) = minimum._1.next()
+    }
+
+    val dists: Array[Long] = ghostDists.values.toArray
+
+    return dists(0)
+  }
+
+  def main(args: Array[String]): Unit = {
+    val solution: Long = solve("./res/day8/input1.txt")
+    println(solution)
+  }
+}