/* 

  Global constraint soft_all_equal_ctr in Picat.

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

   soft_all_equal_ctr​(VARIABLES,​N)

  Purpose

  Consider the equality constraints involving two distinct variables of 
  the collection VARIABLES. Among the previous set of constraints, N is 
  less than or equal to the number of equality constraints that hold.
  
  Example
   ​(6, <5, 1, 5, 5>)

  Within the collection <5, 1, 5, 5> six equality constraints holds. 
  Consequently, the soft_all_equal_ctr constraint holds since the 
  argument N=6 is less than or equal to the number of equality 
  constraints that hold.
  """



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

*/

import cp.

main => go.

go =>
  N = 4,
  X = new_list(N),
  X :: 1..5,

  NN :: 0..N*N,
  
  X = [5,1,5,5],
  % NN #= 6,
  soft_all_equal_ctr(X, NN),

  Vars = X ++ [NN],
  solve(Vars),

  println(x=X),
  println(nn=NN),
  nl,
  fail,
  
  nl.


soft_all_equal_ctr(X, N) => 
  Len = X.len,
  N #>= 0,
  N #<= Len * Len,
  N #<= sum([X[I] #= X[J]  : I in 1..Len, J in 1..Len, I != J]).