class WrongNumberOfPlayersError < StandardError ; end
class NoSuchStrategyError < StandardError ; end

def rps_game_winner(game)
  raise WrongNumberOfPlayersError unless game.length == 2
  valid = /[rps]/
  game1 = game[0][1].downcase
  game2 = game[1][1].downcase
  raise NoSuchStrategyError unless (game1 =~ valid) && (game2 =~ valid)
  get_winner(game1, game2) ? game[0] : game[1]
end

def get_winner(game1, game2)
  if (game1 == game2)
    return true
  end
  if (game1 == 'p' && game2 == 'r') || (game1 == 'r' && game2 == 's') || (game1 == 's' && game2 == 'p')
    return true
  else
    return false
  end
end

def rps_tournament_winner(tournament)
  players = []
  return tournament[0] if tournament.size == 1
  new_array = []
  tournament.flatten.each_slice(2) do |l1|
    new_array << l1
  end
  new_array.each_slice(2) do |l1, l2|
    current_game = []
    current_game << l1
    current_game << l2
    players << rps_game_winner(current_game)
  end

  rps_tournament_winner(players)
end