part2.rb

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

def rps_game_winner(game)
  raise WrongNumberOfPlayersError unless game.length == 2

  player1 = game[0]
  player2 = game[1]

  player1_play = player1[1]
  player2_play = player2[1]
  
  plays = ["R", "P", "S"]

  raise NoSuchStrategyError if !plays.include?(player1_play) || !plays.include?(player2_play)
  
  # An array of two-element arrays:
  #   1) Exhaustive list of possible game outcomes
  #   2) 0 or 1, indicating the index of the winning play
  strats = []
  strats << [["R", "S"], 0]
  strats << [["R", "R"], 0]
  strats << [["R", "P"], 1]
  strats << [["P", "P"], 0]
  strats << [["P", "S"], 1]
  strats << [["P", "R"], 0]
  strats << [["S", "S"], 0]
  strats << [["S", "R"], 1]
  strats << [["S", "P"], 0]

  # Create an array that we'll match against the strategies
  # in the strats array, e.g. ["R", "S"]
  strat = [player1_play, player2_play]

  # Find the matching strategy from strat, and return the correct
  # player using the index
  strats.each do |s|
    return game[s[1]] if strat == s[0]
  end

  # A much simpler solution than this would be to just back for the
  # 3 cases where you return 1 in an if statement, else return 0
 
  raise "Should not get here"
end

def rps_tournament_winner game

  # Recurse until you've drilled down to the first actual game
  play1 = game[0]
  play1 = rps_tournament_winner play1 if play1[0].class == Array

  play2 = game[1]
  play2 = rps_tournament_winner play2 if play2[0].class == Array

  # You're drilled down to an actual game at this point, so
  # compute the winner and let the recursion unroll.
  rps_game_winner([play1, play2])
end

tourn_arr = 
[ 
 [ 
   [ ["Armando", "P"], ["Dave", "S"] ],
   [ ["Richard", "R"],  ["Michael", "S"] ]
 ],
 [
   [ ["Allen", "S"], ["Omer", "P"] ],
   [ ["David E.", "R"], ["Richard X.", "P"] ]
 ] 
]

arr = [ [ "Parker", "R" ], [ "Stew", "P" ] ]

puts rps_game_winner(arr).inspect
puts rps_tournament_winner(tourn_arr).inspect