testing2/knight2.scala
changeset 152 114a89518aea
parent 145 d306102fd33b
--- a/testing2/knight2.scala	Fri Nov 17 14:11:58 2017 +0000
+++ b/testing2/knight2.scala	Tue Nov 21 16:31:11 2017 +0000
@@ -6,7 +6,7 @@
 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 = {
+def print_board(dim: Int, path: Path) : Unit = {
   println
   for (i <- 0 until dim) {
     for (j <- 0 until dim) {
@@ -16,21 +16,21 @@
   } 
 }
 
-def add_pair(x: Pos)(y: Pos): Pos = 
+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 = 
+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] = 
+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] = 
+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 {
+def first(xs: List[Pos], f: Pos => Option[Path]) : Option[Path] = xs match {
   case Nil => None
   case x::xs => {
     val result = f(x)
@@ -41,7 +41,7 @@
 //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] = {
+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))