example/send_most_money.rb in gecoder-0.9.0 vs example/send_most_money.rb in gecoder-0.9.1

@@ -1,58 +1,47 @@
 require File.dirname(__FILE__) + '/example_helper'
 
 # Solves the cryptarithmetic send+most=money problem while maximizing the value
 # of "money".
-class SendMoreMoney < Gecode::Model
+class SendMostMoney
+  include Gecode::Mixin
+
   attr :money
 
   def initialize
     # Set up the variables, 9 letters with domain 0..9.
-    s,e,n,d,m,o,s,t,y = @letters = int_var_array(9, 0..9)
-    @money = wrap_enum([m,o,n,e,y])
+    s,e,n,d,m,o,s,t,y = letters_is_an int_var_array(9, 0..9)
+    # Express the quantity we are optimizing, in this case money.
+    # This utilises that any operand can be converted into a variable.
+    @money = equation_row(m,o,n,e,y).to_int_var
     
     # Set up the constraints.
     # The equation must hold.
     (equation_row(s, e, n, d) + equation_row(m, o, s, t)).must == 
-      equation_row(m,o,n,e,y) 
+      equation_row(m, o, n, e, y) 
     
     # The initial letters may not be 0.
     s.must_not == 0
     m.must_not == 0
     
     # All letters must be assigned different digits.
-    @letters.must_be.distinct
+    letters.must_be.distinct
 
     # Set the branching.
-    branch_on @letters, :variable => :smallest_size, :value => :min
+    branch_on letters, :variable => :smallest_size, :value => :min
   end
 
-  def to_s
-    %w{s e n d m o s t y}.zip(@letters).map do |text, letter|
-      "#{text}: #{letter.value}" 
-    end.join(', ')
-  end
-  
   private
 
   # A helper to make the linear equation a bit tidier. Takes a number of
   # variables and computes the linear combination as if the variable
   # were digits in a base 10 number. E.g. x,y,z becomes
   # 100*x + 10*y + z .
   def equation_row(*variables)
-    variables.to_number
+    variables.inject{ |result, variable| variable + result * 10 }
   end
 end
 
-class Array
-  # Computes a number of the specified base using the array's elements as 
-  # digits.
-  def to_number(base = 10)
-    inject{ |result, variable| variable + result * base }
-  end
-end
-
-solution = SendMoreMoney.new.optimize! do |model, best_so_far|
-  model.money.to_number.must > best_so_far.money.values.to_number
-end
-puts solution.to_s
-puts "money: #{solution.money.values.to_number}"
+solution = SendMostMoney.new.maximize! :money
+puts 's e n d m o s t y'
+puts solution.letters.values.join(' ')
+puts "money: #{solution.money.value}"