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2019/Scala/day06/Counter.scala

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+package day06
+
+class Counter
+{
+  private[this] var counter: Int = 0
+  def count: Int = counter
+  def inc(n: Int): Unit = counter += n
+}

2019/Scala/day06/Day06.scala

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+package day06
+
+import scala.collection.mutable
+
+class Day06(input: List[String])
+{
+  /** Easy access to all nodes */
+  val nodes = new mutable.HashMap[String, Node]
+
+  /** list of tuples */
+  val tuples: List[(String, String)] = input.map(string => {
+    val split = string.split(')')
+    (split(0), split(1))
+  })
+
+  tuples.foreach(tuple => {
+    val (a , b) = tuple
+    if (!nodes.contains(a)) nodes.addOne(a, new Node(a))
+    if (!nodes.contains(b)) nodes.addOne(b, new Node(b))
+  })
+
+  tuples.foreach(tuple => {
+    val (a , b) = tuple
+    nodes(a).children += nodes(b)
+    nodes(b).parent = nodes(a)
+  })
+
+  def solveP1(): Int =
+  {
+    val start: Node = nodes("COM")
+    val counter = new Counter
+    start.countDepths(0, counter)
+    counter.count
+  }
+
+  def solveP2(): Int =
+  {
+    val start = nodes("YOU")
+    val end = nodes("SAN")
+    val youParents = start.getParents
+    val mergePoint = end.findFirstCommon(youParents)
+    start.findDistanceToParent(mergePoint) + end.findDistanceToParent(mergePoint)
+  }
+
+}

2019/Scala/day06/Main.scala

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+package day06
+
+import kamlib.{Reader, Wrapper}
+
+object Main {
+
+  def main(args: Array[String]): Unit = {
+    val input: List[String] = Reader.readList("/input6.txt")
+    val tuple = Wrapper(new Day06(input)).tuple
+    println(s"Time initializing data structures: ${tuple._2}ms")
+    val solution = tuple._1
+
+    println("Part 1:")
+    Wrapper(solution.solveP1()).print()
+    println("Part 2:")
+    Wrapper(solution.solveP2()).print()
+  }
+}

2019/Scala/day06/Tree.scala

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+package day06
+
+import scala.collection.mutable
+
+sealed trait Tree
+case object Leaf extends Tree
+case class Node(name: String, var parent: Tree = Leaf) extends Tree
+{
+  val children = new mutable.ArrayBuffer[Node]
+
+  def countDepths(depth: Int, counter: Counter): Unit =
+  {
+    counter.inc(depth)
+    children.foreach(child => {
+      child.countDepths(depth+1, counter)
+    })
+  }
+
+  def getParents: List[Node] =
+    parent match
+    {
+      case Leaf => List()
+      case p: Node => p::p.getParents
+    }
+
+  def findFirstCommon(nodes: List[Node]): Node =
+  {
+    parent match
+    {
+      case Leaf => throw new Exception("Something went wrong")
+      case p: Node => if (nodes.contains(p)) p else p.findFirstCommon(nodes)
+    }
+  }
+
+  def findDistanceToParent(target: Node, acc: Int = 0): Int =
+  {
+    parent match
+    {
+      case Leaf => throw new Exception("Something went wrong")
+      case p: Node => if (p == target) acc else p.findDistanceToParent(target, acc+1)
+    }
+  }
+}