Hacker Rank Goodnode challenge

goodNode.scala

package com.example
import scala.collection.mutable.HashMap

class Node(idx : Int) {
  val index = idx
  var pointsTo : Option[Node] = None
  var walked = false
  override def toString() = s"Node - idx: ${this.index}, points to ${this.pointsTo.get.index}."
}

object EndsInBadNode {
  def apply(node : Node) = node
  def unapply(node : Node) : Option[Node] = {
    //println(s"Deep in $node")
    if (node.pointsTo.get.index == 0) return None
    if (node.index == node.pointsTo.get.index) {
      node.walked = false
      return Some(node)
    }
    if (node.pointsTo.get.walked) {
      return Some(node)
    }
    node.walked = true // protects agains dead lock
    val bad = node.pointsTo.get match {
      case EndsInBadNode(n) => Some(n)
      case _ => None
    }
    node.walked = false
    return bad
  }
}


object Solution {
  var pool = HashMap[Int, Node]()

  def init(size : Int) {
    // simple clean up
    this.moves = 0
    this pool = this.pool.empty
    //
    for (i <- 0 until size) {
      this.pool += (i -> new Node(i))
    }
  }

  def connect(index : Int, targetIndex : Int) {
    this.pool.get(index).map { _.pointsTo = this.pool.get(targetIndex) }
  }

  var moves : Int = 0

  def solve(n : Node) : Unit = {
    n match {
      case EndsInBadNode(n) => {
        //println(s"Node ${n.index} is dead. Reconnecting...")
        this.connect(n.index, 0)
        this.moves += 1
      }
      case _ => Unit
    }
  }

  def run(values : List[Int]) {
    val length = values.length
    this.init(length)
    values.zipWithIndex foreach {
      case (v, i) => this.connect(i, v)
    }
    for (n <- 0 until length) {
      //println(s"Testing : $n")
      solve(this.pool(n))
    }
  }

  def main(args: Array[String]): Unit = {
      // my tail node is 0 instead of 1
      run(List(1,2,1)) // -> prints 1
      println(s"Total moves: ${this.moves}")
      run(List(1,2,3,2)) // -> prints 1
      println(s"Total moves: ${this.moves}")
      run(List(3,0,2,2,4)) //-> prints 2
      println(s"Total moves: ${this.moves}")
      run(List(4,4,4,4,4)) //-> prints 1
      println(s"Total moves: ${this.moves}")
  }
}