diff -r 5e489c9fe47b -r b5f3e814a710 marking2/knight2.scala
--- a/marking2/knight2.scala	Fri Nov 30 13:06:09 2018 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,61 +0,0 @@
-// Part 2 about finding a single tour for a board
-//================================================
-
-object CW7b {
-
-type Pos = (Int, Int)    // a position on a chessboard 
-type Path = List[Pos]    // a path...a list of positions
-
-def print_board(dim: Int, path: Path) : Unit = {
-  println
-  for (i <- 0 until dim) {
-    for (j <- 0 until dim) {
-      print(f"${path.reverse.indexOf((i, j))}%3.0f ")
-    }
-    println
-  } 
-}
-
-def add_pair(x: Pos)(y: Pos) : Pos = 
-  (x._1 + y._1, x._2 + y._2)
-
-def is_legal(dim: Int, path: Path)(x: Pos) : Boolean = 
-  0 <= x._1 && 0 <= x._2 && x._1 < dim && x._2 < dim && !path.contains(x)
-
-def moves(x: Pos) : List[Pos] = 
-  List(( 1,  2),( 2,  1),( 2, -1),( 1, -2),
-       (-1, -2),(-2, -1),(-2,  1),(-1,  2)).map(add_pair(x))
-
-def legal_moves(dim: Int, path: Path, x: Pos) : List[Pos] = 
-  moves(x).filter(is_legal(dim, path))
-
-
-def first(xs: List[Pos], f: Pos => Option[Path]) : Option[Path] = xs match {
-  case Nil => None
-  case x::xs => {
-    val result = f(x)
-    if (result.isDefined) result else first(xs, f)
-  }
-}
-
-//first(List((1, 0),(2, 0),(3, 0),(4, 0)), (x => if (x._1 > 3) Some(List(x)) else None))
-//first(List((1, 0),(2, 0),(3, 0)), (x => if (x._1 > 3) Some(List(x)) else None))
-
-def first_tour(dim: Int, path: Path) : Option[Path] = {
-  if (path.length == dim * dim) Some(path)
-  else
-    first(legal_moves(dim, path, path.head), (x: Pos) => first_tour(dim, x::path))
-}
-
-/* 
-val ts1 = first_tour(8, List((0, 0))).get
-  assert(correct_urban(8)(ts1) == true)
-
-val ts2 = first_tour(4, List((0, 0)))
-assert(ts2 == None)  
-
-print_board(8, first_tour(8, List((0, 0))).get)
-*/
-
-}
-