--- 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))