HW impossibility?: “Create a rock paper scissors program in ruby WITHOUT using conditionals”

Question

I\'m in an introductory software development class, and my homework is to create a rock paper scissors program that takes two arguments (rock, paper), etc, and returns the arg t

Answer 1

I just think the simplest solution has to be something like:

@results = {
  'rock/paper' => 'paper',
  'rock/scissors' => 'rock',
  'paper/scissors' => 'scissors',
  'paper/rock' => 'paper',
  'scissors/paper' => 'scissors',
  'scissors/rock' => 'rock'
}

def winner p1, p2
  @results["#{p1}/#{p2}"]
end

Answer 2

I don't know much about ruby, but I solved a problem like this long ago by using values for each one (eg, R = 1, P = 2, S=3).

Actually, I just googled after thinking about that and someone solved the problem in python using an array.

Answer 3

Here's one only using hashes:

RULES = {
  :rock     => {:rock => :draw, :paper => :paper, :scissors => :rock},
  :paper    => {:rock => :paper, :paper => :draw, :scissors => :scissors},
  :scissors => {:rock => :rock, :paper => :scissors, :scissors => :draw}
}

def play(p1, p2)
  RULES[p1][p2]
end

puts play(:rock, :paper)        # :paper
puts play(:scissors, :rock)     # :rock
puts play(:scissors, :scissors) # :draw

Answer 4

I very much doubt you've seen array/set intersections, so just for fun:

def who_wins(p1, p2)
  win_moves = {"rock" => "paper", "paper" => "scissors", "scissors" => "rock"}
  ([p1, p2] & win_moves.values_at(p1, p2)).first
end

who_wins("rock", "paper") # "paper"
who_wins("scissors", "rock") # "rock"
who_wins("scissors", "scissors") # nil

Answer 5

A simple hash to the rescue:

def tell_me(a1, a2)
  input = [a1 , a2].sort.join('_').to_sym
  rules = { :paper_rock => "paper", :rock_scissor => "rock", :paper_scissor => "scissor"}
  rules[input]
end

Answer 6

WINNAHS = [[:rock, :scissors], [:scissors, :paper], [:paper, :rock]]

def winner(p1, p2)
  (WINNAHS.include?([p1,p2]) && p1) || (WINNAHS.include?([p2,p1]) && p2) || :tie
end

winner(:rock, :paper)        #=> :paper 
winner(:scissors, :paper)    #=> :scissors 
winner(:scissors, :scissors) #=> :tie