/* 

  Global constraint product_ctr in Picat.

  From Global Constraint Catalogue
  http://www.emn.fr/x-info/sdemasse/gccat/Cproduct_ctr.html
  """
  Constraint

      product_ctr(VARIABLES,CTR,VAR)

  Purpose

      Constraint the product of a set of domain variables. More precisely, 
      let P denote the product of the variables of the VARIABLES collection. 
      Enforce the following constraint to hold: P CTR VAR.

  Example
      (<2,1,4>,=,8)

      The product_ctr constraint holds since its last argument VAR=8 is 
      equal (i.e., CTR is set to =) to 2*1*4.
  """ 

 
  This Picat model was created by Hakan Kjellerstrand, hakank@gmail.com
  See also my Picat page: http://www.hakank.org/picat/

*/

import cp.


main => go.

go ?=>
  N = 3,
  Variables = new_list(N),
  Variables :: 1..4,
  
  Ctr = #=,
  TVar :: 0..1000,

  Variables = [2,1,4],
  % TVar #= 8,

  product_ctr(Variables, Ctr, TVar),

  Vars = Variables ++ [TVar],
  solve(Vars),

  println(variables=Variables),
  println(tvar=TVar),
  nl,
  fail,
  
  nl.

go => true.


product_ctr(Variables,Ctr,TVar) =>
  Res #= prod(Variables),
  call(Ctr,Res,TVar).