Final refactoring of anomaly script.

ruby/finalfantasyxiii2_anomaly.rb

@@ -7,17 +7,20 @@
   where the Xs are the values of the nodes numbered 0 to n clockwise.
   You can pick 0 arbitrarily.
   
+  Output: An array of clock indices to visit in sequence.
+  
   This script brute-forces the clock anomaly puzzles found in 
   the temporal rifts around the timeline. Because the script
-  maintains a global state during the recursion (versus passing a 
-  copy of the state throughout each step), it could probably handle 
-  some really large versions of the puzzle.
+  maintains a global state during the recursion (versus passing
+  copies throughout each step), it could probably handle some 
+  really large versions of the puzzle.
   
   04/19/2012 - original
-  04/20/2012 - initial cleanup, command-line argument
+  04/20/2012 - refactoring
   
 =end
 
+
 # GLOBAL STATE
 
 # The clock is represented as an array of pairs of the form [value, active?].
@@ -37,14 +40,6 @@ def value(index)
   $clock[index][0]
 end
 
-def upper(start)
-  (start + value(start)) % $clock.length
-end
-
-def lower(start)
-  (start - value(start)) % $clock.length
-end
-
 # Checks if a node is empty.
 def empty?(index)
   not $clock[index][1]
@@ -56,49 +51,45 @@ def win?
 end
 
 # Checks if both clock hands point to empty nodes.
-def lose?(hand1, hand2)
-  empty?(hand1) and empty?(hand2)
+def lose?
+  empty?($hands[0]) and empty?($hands[1])
 end
 
 # Updates the clock hands based on a move.
 def update_hands(move)
   $hands = [-value(move), value(move)].map{|h| (h + move) % $clock.length}
-  $hands = [(move - value(move)) % $clock.length, (move + value(move)) % $clock.length]
 end
 
 # Executes the move, updates state, and returns the new positions of the clock hands.
 def execute(move)
   $moves << move
   $clock[move][1] = false
+  update_hands(move)
 end
 
 # Reverts the state to before the last move.
 def revert
   $clock[$moves.pop][1] = true
+  update_hands($moves[-1])
 end
 
 
-# RECURSIVE FUNCTION
+# SCRIPT LOGIC
 
 def do_move(move)
   return if empty?(move)
-  h1 = lower(move)
-  h2 = upper(move)
   execute(move)
   if win?
     puts $moves.inspect
     exit
-  elsif lose?(h1, h2)
+  elsif lose?
     revert and return
   else
-    do_move(h1)
-    do_move(h2)
+    do_move($hands[0])
+    do_move($hands[1])
     revert and return
   end
 end
 
-
-# EXECUTION
-
 (0..($clock.length - 1)).each{|start| do_move(start)}