Bowling Swift

bowling.swift

class Frame {
  var one: Int
  var two: Int?
  var extras: [Int]

  init(one: Int, two: Int?) {
    self.one = one
    self.two = two
    self.extras = [Int]()
  }

  func score() -> Int {
    return rolls() + self.extras.reduce(0) { $0 + $1 }
  }

  func close(following: Frame) -> Frame {
    if isClosed() {
      return self
    } else {
      return takeExtras(following)
    }
  }

  private func isClosed() -> Bool {
    return (rolls() < 10) ||
      (self.one == 10 && self.extras.count == 2) ||
      (self.one != 10 && rolls() == 10 && self.extras.count == 1)
  }

  private func rolls() -> Int {
    if (self.two == nil) {
      return self.one
    } else {
      return self.one + self.two!
    }
  }

  private func takeExtras(following: Frame) -> Frame {
    if (self.one == 10) {
      self.extras.append(following.one)
      if (following.two != nil && self.extras.count != 2) {
        self.extras.append(following.two!)
      }
      return self
    } else {
      self.extras.append(following.one)
      return self
    }
  }
}

func newFrame(one: Int, _ two: Int) -> Frame {
  return Frame(one: one, two: two)
}

func newFrame(one: Int) -> Frame {
  return Frame(one: one, two: nil)
}

typealias Score = (frames: [Int], total: Int)

func bowlingScore(frames: [Frame]) -> Score {
  let scores = frames.reduce([Frame]()) { (prev, frame) in
    return prev.map { (f) in f.close(frame) } + [frame]
  }.map { $0.score() }[0...9]
  return Score(Array(scores), scores.reduce(0) { $0 + $1 })
}

let game1 = [Frame](count: 10, repeatedValue: newFrame(0, 0))
print(bowlingScore(game1))

let game2 = [Frame](count: 10, repeatedValue: newFrame(0, 1))
print(bowlingScore(game2))

let game3 = [Frame](count: 12, repeatedValue: newFrame(10))
print(bowlingScore(game3))

let game4 = [
  newFrame(10), // 30
  newFrame(10), // 28
  newFrame(10), // 18
  newFrame(8, 0), // 8
  newFrame(0, 8), // 8
  newFrame(7, 1), // 8
  newFrame(9, 1), // 17
  newFrame(7, 1), // 8
  newFrame(7, 1), // 8
  newFrame(5, 0) // 5
] // 138
print(bowlingScore(game4))