ex1search

package lecture9.exercises.cp.search




import oscar.cp.modeling._
import oscar.cp.core._
import oscar.algo.reversible.ReversibleInt

/**
 * @author Pierre Schaus pschaus@gmail.com
 */
object Exercise01 extends App {

  implicit val cp = CPSolver()

  val a = Array.fill(20)(0)

  val i = new ReversibleInt(cp,0)

  var nbSol = 0

  onSolution {
    //println(a.mkString(","))
    nbSol += 1
  }

  search {
    if (i >= a.size) noAlternative
    else branch {
      //left
      if(a.sum >= 3)
          cp.fail()
      else
        a(i) = 1
      i += 1
    } {
      //right
      a(i) = 0
      i += 1
    }
  }
  start()
  print(nbSol)

}

/*

Hint: Doc of most of OscaR constraints are available here:
      https://jenkins.info.ucl.ac.be:8080/job/oscar-dev/javadoc/?#oscar.cp.modeling.Constraints
      A good Scala cheat sheet available here:
      http://docs.scala-lang.org/cheatsheets/

1) run this program

2) modify it to print all possible 0/1 assignments on a

3) modify it to print the solution in this order

1,1,1
1,1,0
1,0,1
1,0,0

4) Increase the size of a to 20 and count the number of solution

5) cutoff branches where there  are at more than three 1's, how many solutions?
   Hint: use cp.fail() in a branch:

         cp.branch {
           left branch
           if (condition) cp.fail()
           else ...
         } {
           right branch
         }

   How many solutions are there?
*/