1 

     2 import scala.concurrent._

     3 import scala.concurrent.duration._

     4 import ExecutionContext.Implicits.global

     5 import scala.language.postfixOps 

     6 

     7 

     8 def add_pair_urban(x: Pos)(y: Pos): Pos = 

     9   (x._1 + y._1, x._2 + y._2)

    10 

    11 def is_legal_urban(dim: Int, path: Path)(x: Pos): Boolean = 

    12   0 <= x._1 && 0 <= x._2 && x._1 < dim && x._2 < dim && !path.contains(x)

    13 

    14 def moves_urban(x: Pos): List[Pos] = 

    15   List(( 1,  2),( 2,  1),( 2, -1),( 1, -2),

    16        (-1, -2),(-2, -1),(-2,  1),(-1,  2)).map(add_pair_urban(x))

    17 

    18 def legal_moves_urban(dim: Int, path: Path, x: Pos): List[Pos] = 

    19   moves_urban(x).filter(is_legal_urban(dim, path))

    20 

    21 def correct_urban(dim: Int)(p: Path): Boolean = p match {

    22   case Nil => true

    23   case x::Nil => true

    24   case x::y::p => 

    25     if (legal_moves_urban(dim, p, y).contains(x)) correct_urban(dim)(y::p) else false

    26 }

    27 

    28 

    29 lazy val f1 = Future {

    30 

    31   val ts8 = first_tour_heuristic(8, List((0,0))).get

    32   assert(correct_urban(8)(ts8) == true)

    33 

    34 }

    35 

    36 Await.result(f1, 360 second)

    37 

    38 lazy val f2 = Future {

    39 

    40   val ts50 = first_tour_heuristic(50, List((0,0))).get

    41   assert(correct_urban(50)(ts50) == true)

    42 

    43 }

    44 

    45 Await.result(f2, 360 second)