Past exam of the year 1 of the computer science course of the University of Oxford / 2016 / Imperative programming / 6 / d

def cards: List[Int] = _cards
def cards_=(cs: List[Int]): Unit = { _cards = cs }
def visibleValue: Int = _visibleValue
def visibleValue_=(v: Int): Unit = { _visibleValue = v }

class Regular extends Player {
  def play(visibleCards: List[Int]): Boolean = {
    require(visibleCards.length == 1)
    val total = value
    if (total < 21 && total <= 21 - visibleCards.head) {
      hit
      true
    } else false
  }
}

class Optimistic extends Player {
  def play(visibleCards: List[Int]): Boolean = {
    if (value != 21) {
      hit
      true
    } else false
  }
}

class House extends Player {
  def play(visibleCards: List[Int]): Boolean = {
    val total = value
    if (total < 21 && visibleCards.forall(v => total <= 21 - v)) {
      hit
      true
    } else false
  }
}