import scala.collection.mutable

class Hanoi(val n: Int, val left: Char, val mid: Char, val right: Char) {
  val lists: mutable.HashMap[Char, mutable.Stack[Int]] = new mutable.HashMap()
  lists(left) = mutable.Stack.range(1, n + 1)
  lists(mid) = mutable.Stack.empty
  lists(right) = mutable.Stack.empty

  def move(from: Char, to: Char): Unit = {
    val i: Int = lists(from).pop()
    println(s"Moving disk $i from $from->$to")
    lists(to).push(i)
  }

  def solve(): Unit = {
    hanoi(n, left, mid, right)
  }

  private def hanoi(n: Int, start: Char, aux: Char, end: Char): Unit = {
    if (n == 0) return
    hanoi(n - 1, start, end, aux)
    move(start, end)
    hanoi(n - 1, aux, start, end)
  }
}

object Hanoi {
  def main(args: Array[String]): Unit = {
    val hanoi: Hanoi = new Hanoi(3, 'A', 'B', 'C')
    hanoi.solve()
  }
}