From e6586027238a750768fd6cc75b226eec87086bd2 Mon Sep 17 00:00:00 2001
From: Adam Coffman <acoffman@wustl.edu>
Date: Wed, 5 Jan 2022 20:17:52 -0600
Subject: [PATCH] initial implementation of FlipFlop in Ruby

---
 36_Flip_Flop/ruby/flipflop.rb | 162 ++++++++++++++++++++++++++++++++++
 1 file changed, 162 insertions(+)
 create mode 100644 36_Flip_Flop/ruby/flipflop.rb

diff --git a/36_Flip_Flop/ruby/flipflop.rb b/36_Flip_Flop/ruby/flipflop.rb
new file mode 100644
index 00000000..3a65a4c2
--- /dev/null
+++ b/36_Flip_Flop/ruby/flipflop.rb
@@ -0,0 +1,162 @@
+#A class representing the internal state of a single game of flip flop
+# state represents the list of X's (A in the original code)
+# guesses represents the number of guesses the user has made (C in the original code)
+# seed represents the random seed for an instance of the game (Q in the original code)
+Game = Struct.new(:state, :guesses, :seed) do
+
+  #The original BASIC program used 1 indexed arrays while Ruby has 0-indexed arrays.
+  #We can't use 0 indexed arrays for the flip functions or we'll get divide by zero errors.
+  #These convenience functions allow us to modify and access internal game state in a 1-indexed fashion
+  def flip_letter(letter_number)
+    index = letter_number -1
+    if self.state[index] == 'X'
+      self.state[index] = 'O'
+    else
+      self.state[index] = 'X'
+    end
+  end
+
+  def letter_at(letter_number)
+    self.state[letter_number - 1]
+  end
+end
+
+def print_welcome
+  puts 'FLIPFLOP'.center(72)
+  puts 'CREATIVE COMPUTING  MORRISTOWN, NEW JERSEY'.center(72)
+  puts <<~EOS
+
+    THE OBJECT OF THIS PUZZLE IS TO CHANGE THIS:
+
+    X X X X X X X X X X
+
+    TO THIS:
+
+    O O O O O O O O O O
+
+    BY TYPING THE NUMBER CORRESPONDING TO THE POSITION OF THE
+    LETTER ON SOME NUMBERS, ONE POSITION WILL CHANGE, ON
+    OTHERS, TWO WILL CHANGE.  TO RESET LINE TO ALL X'S, TYPE 0
+    (ZERO) AND TO START OVER IN THE MIDDLE OF A GAME, TYPE
+    11 (ELEVEN).
+  EOS
+end
+
+def print_starting_message
+  puts <<~EOS
+
+  HERE IS THE STARTING LINE OF X'S.
+
+  1 2 3 4 5 6 7 8 9 10
+  X X X X X X X X X X
+  
+  EOS
+end
+
+#Create a new game with [X,X,X,X,X,X,X,X,X,X] as the state
+#0 as the number of guesses and a random seed between 0 and 1
+def generate_new_game
+  Game.new(Array.new(10, 'X'), 0, rand())
+end
+
+#Given a game, an index, and a shuffle function, flip one or more letters
+def shuffle_board(game, index, shuffle_function)
+  n = method(shuffle_function).call(game, index)
+
+  if game.letter_at(n) == "O"
+    game.flip_letter(n)
+    if index == n
+      n = shuffle_board(game, index, shuffle_function)
+    end
+  else
+    game.flip_letter(n)
+  end
+  return n
+end
+
+#Shuffle logic copied from original BASIC code
+def shuffle_function1(game, index) 
+  r = Math.tan(game.seed + index / game.seed - index) - Math.sin(game.seed / index) + 336 * Math.sin(8 * index)
+  n = r - r.floor
+  (10 * n).floor
+end
+
+def shuffle_function2(game, index)
+  r = 0.592 * (1/ Math.tan(game.seed / index + game.seed)) / Math.sin(index * 2 + game.seed) - Math.cos(index)
+  n = r - r.floor
+  (10 * n)
+end
+
+def play_game
+  print_starting_message
+  game = generate_new_game
+  working_index = nil
+
+  loop do
+    puts "INPUT THE NUMBER"
+    input = gets.chomp.downcase
+
+    #See if the user input a valid integer, fail otherwise
+    if numeric_input = Integer(input, exception: false)
+
+      #If 11 is entered, we're done with this version of the game
+      if numeric_input == 11
+        return :restart
+      end
+
+      if numeric_input > 11
+        puts 'ILLEGAL ENTRY--TRY AGAIN.'
+        next #illegal entries don't count towards your guesses
+      end
+
+      if working_index == numeric_input
+        game.flip_letter(numeric_input)
+        working_index = shuffle_board(game, numeric_input, :shuffle_function2)
+      #If 0 is entered, we want to reset the state, but not the random seed or number of guesses and keep playing
+      elsif numeric_input == 0
+        game.state = Array.new(10, 'X')
+      elsif game.letter_at(numeric_input) == "O"
+        game.flip_letter(numeric_input)
+        if numeric_input == working_index
+          working_index = shuffle_board(game, numeric_input, :shuffle_function1)
+        end
+      else
+        game.flip_letter(numeric_input)
+        working_index = shuffle_board(game, numeric_input, :shuffle_function1)
+      end
+    else
+      puts 'ILLEGAL ENTRY--TRY AGAIN.'
+      next #illegal entries don't count towards your guesses
+    end
+
+    game.guesses += 1
+    puts '1 2 3 4 5 6 7 8 9 10'
+    puts game.state.join(' ')
+    
+    if game.state.all? { |x| x == 'O' }
+      if game.guesses > 12 
+        puts "TRY HARDER NEXT TIME. IT TOOK YOU #{game.guesses} GUESSES."
+      else
+        puts "VERY GOOD.  YOU GUESSED IT IN ONLY #{game.guesses} GUESSES."
+      end
+      #game is complete
+      return
+    end
+  end
+end
+
+
+
+#Execution starts
+print_welcome
+loop do
+  result = play_game
+  if result == :restart
+    next
+  end
+
+  puts 'DO YOU WANT TO TRY ANOTHER PUZZLE'
+  if gets.chomp.downcase[0] == 'n'
+    break
+  end
+end