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package examples
// Game contains the state of a bowling game.
type Game struct {
rolls []int
current int
}
// NewGame allocates and starts a new game of bowling.
func NewGame() *Game {
game := new(Game)
game.rolls = make([]int, maxThrowsPerGame)
return game
}
// Roll rolls the ball and knocks down the number of pins specified by pins.
func (self *Game) Roll(pins int) {
self.rolls[self.current] = pins
self.current++
}
// Score calculates and returns the player's current score.
func (self *Game) Score() (sum int) {
for throw, frame := 0, 0; frame < framesPerGame; frame++ {
if self.isStrike(throw) {
sum += self.strikeBonusFor(throw)
throw += 1
} else if self.isSpare(throw) {
sum += self.spareBonusFor(throw)
throw += 2
} else {
sum += self.framePointsAt(throw)
throw += 2
}
}
return sum
}
// isStrike determines if a given throw is a strike or not. A strike is knocking
// down all pins in one throw.
func (self *Game) isStrike(throw int) bool {
return self.rolls[throw] == allPins
}
// strikeBonusFor calculates and returns the strike bonus for a throw.
func (self *Game) strikeBonusFor(throw int) int {
return allPins + self.framePointsAt(throw+1)
}
// isSpare determines if a given frame is a spare or not. A spare is knocking
// down all pins in one frame with two throws.
func (self *Game) isSpare(throw int) bool {
return self.framePointsAt(throw) == allPins
}
// spareBonusFor calculates and returns the spare bonus for a throw.
func (self *Game) spareBonusFor(throw int) int {
return allPins + self.rolls[throw+2]
}
// framePointsAt computes and returns the score in a frame specified by throw.
func (self *Game) framePointsAt(throw int) int {
return self.rolls[throw] + self.rolls[throw+1]
}
const (
// allPins is the number of pins allocated per fresh throw.
allPins = 10
// framesPerGame is the number of frames per bowling game.
framesPerGame = 10
// maxThrowsPerGame is the maximum number of throws possible in a single game.
maxThrowsPerGame = 21
)
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