The scoring system for tennis works like this:

• A game is won by the first player to have won at least four points in total and at least two points more than the opponent.

• The running score of each game is described in a manner peculiar to tennis: scores from zero to three points are described as 0, 15, 30, 40, respectively

• If at least three points have been scored by each player, and the scores are equal, the score is "deuce".

• If at least three points have been scored by each side and a player has one more point than his opponent, the score of the game is "advantage" for the player in the lead.

Constraints

• We're just worried about one game, don't worry about sets, tie breakers, etc
• Don't worry about validation, assume the client passes in correct data

For example:

The interface will look something like this in Ruby:

  game = Game.new("player 1", "player 2")
  game.point_won_by("player 1")
  game.point_won_by("player 2")
  // this will return "15-15"
  game.score

  game.point_won_by("player 1")
  game.point_won_by("player 1")
  // this will return "40-15"
  game.score

  game.point_won_by("player 2")
  game.point_won_by("player 2")
  // this will return "Deuce"
  game.score

  game.point_won_by("player 1")
  // this will return "Advantage player 1"
  game.score

  game.point_won_by("player 1")
  // this will return "Player 1 wins"
  game.score