--- a/testing3/knight1.scala	Thu Nov 29 17:15:11 2018 +0000
+++ b/testing3/knight1.scala	Fri Nov 30 03:44:27 2018 +0000
@@ -7,39 +7,44 @@
 // at the end are of any help.
 
 
+
 type Pos = (Int, Int)    // a position on a chessboard 
 type Path = List[Pos]    // a path...a list of positions
 
 //(1) Complete the function that tests whether the position x
 //    is inside the board and not yet element in the path.
 
-def is_legal(dim: Int, path: Path, x: Pos) : Boolean = ((!(path.contains(x))) && (x._1 < dim) && (x._2 < dim))
+def is_legal(dim: Int, path: Path, x: Pos) : Boolean = {
+ if ((x._1 < dim && x._2 < dim) && !(path.contains(x)))
+  true 
+    else 
+  false
+}
 
 
 
 //(2) Complete the function that calculates for a position x
 //    all legal onward moves that are not already in the path. 
 //    The moves should be ordered in a "clockwise" manner.
+ 
 
+def legal_moves(dim: Int, path: Path, x: Pos) : List[Pos] = {
+  val legalMovesList = List((x._1 + 1, x._2 + 2), (x._1 + 2, x._2 + 1), (x._1 + 2, x._2 - 1), (x._1 + 1, x._2 - 2), (x._1 - 1, x._2 - 2), (x._1 - 2, x._2 - 1), (x._1 - 2, x._2 + 1), (x._1 - 1, x._2 + 2))
 
-def legal_moves(dim: Int, path: Path, x: Pos) : List[Pos] ={
-  val y = List((x._1 + 1, x._2 + 2),
-               (x._1 + 2, x._2 + 1),
-               (x._1 + 2, x._2 - 1),
-               (x._1 + 1, x._2 - 2),
-               (x._1 - 1, x._2 - 2),
-               (x._1 - 2, x._2 - 1),
-               (x._1 - 2, x._2 + 1),
-               (x._1 - 1, x._2 + 2)
-   )
-  y.filter(next => is_legal(dim, path, next))
+  for (i <- legalMovesList
+    if (is_legal(dim, path, i)))
+      yield i
+
 }
 
+
 //some test cases
 //
-//assert(legal_moves(8, Nil, (2,2)) == List((3,4), (4,3), (4,1), (3,0), (1,0), (0,1), (0,3), (1,4)))
+//assert(legal_moves(8, Nil, (2,2)) == 
+//  List((3,4), (4,3), (4,1), (3,0), (1,0), (0,1), (0,3), (1,4)))
 //assert(legal_moves(8, Nil, (7,7)) == List((6,5), (5,6)))
-//assert(legal_moves(8, List((4,1), (1,0)), (2,2)) ==  List((3,4), (4,3), (3,0), (0,1), (0,3), (1,4)))
+//assert(legal_moves(8, List((4,1), (1,0)), (2,2)) == 
+//  List((3,4), (4,3), (3,0), (0,1), (0,3), (1,4)))
 //assert(legal_moves(8, List((6,6)), (7,7)) == List((6,5), (5,6)))
 
 
@@ -49,35 +54,43 @@
 //    and the second collects all tours in a list of paths.
 
 def count_tours(dim: Int, path: Path) : Int = {
-  if(path.length == dim*dim) 1 else
-    (for(i <- legal_moves(dim, path, path.head)) yield
-      count_tours(dim, i :: path)
-    ).sum
+  if (path.size == (dim ^ 2)){
+    List(path).size
+  }  else {
+    val totalTours = legal_moves(dim, path, path.head) 
+    totalTours.map(element => count_tours(dim, element :: path)).sum
+  } 
 }
 
-def enum_tours(dim: Int, path: Path) : List[Path] ={
-  if(path.length == dim*dim) List(path) else
-    (for(i <- legal_moves(dim, path, path.head)) yield
-      enum_tours(dim, i :: path)
-    ).flatten
+def enum_tours(dim: Int, path: Path) : List[Path] = {
+  if (path.size == (dim ^ 2)){
+    List(path)
+  } else {
+    val totalEnums = legal_moves(dim, path, path.head)
+    totalEnums.map(element => enum_tours(dim, element :: path)).flatten
+  }
 }
 
+
 //(5) Implement a first-function that finds the first 
 //    element, say x, in the list xs where f is not None. 
 //    In that case Return f(x), otherwise None. If possible,
 //    calculate f(x) only once.
 
 def first(xs: List[Pos], f: Pos => Option[Path]) : Option[Path] = {
-  if(xs == Nil) None
-  else(
-    for(x <- xs) yield{
-      val a = f(x)
-      if(a != None) a
-      else first(xs.drop(1), f)
+  if (xs eq Nil) {
+    None
+  } else {
+    if (f(xs.head) != None) {
+      f(xs.head)
+    } else {
+      first(xs.tail, f)
     }
-  ).head
+  }
+
 }
 
+
 // test cases
 //def foo(x: (Int, Int)) = if (x._1 > 3) Some(List(x)) else None
 //
@@ -92,10 +105,13 @@
 //    knight tour on a dim * dim-board.
 
 
-// def first_tour(dim: Int, path: Path) : Option[Path] = {
-//   first(legal_moves(dim, path, path.head), (x : Pos => ))
-// }
+//def first_tour(dim: Int, path: Path) : Option[Path] = ...
  
+
+
+
+
+
 /* Helper functions