The state, holds the current window and the optimum (so far) window

state.scala

case class State[Container](current: Window, best: Window, contained: Container) {
  def lastIndex(): Int = current.r
  def firstIndex(): Int = current.l
  override def toString =
    s"current: [${current.l}, ${current.r}], best: [${best.l}, ${best.r}], excess: ${contained}"
}