--- a/progs/k1_sol.scala	Wed Nov 16 14:37:18 2016 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,132 +0,0 @@
-// Part 1 about finding anod counting Knight's tours
-//===================================================
-
-
-
-type Pos = (Int, Int)
-type Path = List[Pos]
-
-def print_board(dim: Int, path: Path): Unit = {
-  println
-  for (i <- 0 until dim) {
-    for (j <- 0 until dim) {
-      print(f"${path.reverse.indexOf((i, j))}%3.0f ")
-    }
-    println
-  } 
-}
-
-def add_pair(x: Pos)(y: Pos): Pos = 
-  (x._1 + y._1, x._2 + y._2)
-
-def dist(dim: Int, y: Pos) = 
-  (dim / 2 - y._1).abs + (dim / 2 - y._2).abs
-
-def is_legal(dim: Int, path: Path)(x: Pos): Boolean = 
-  0 <= x._1 && 0 <= x._2 && x._1 < dim && x._2 < dim && !path.contains(x)
-
-def moves(x: Pos): List[Pos] = 
-  List(( 1,  2),( 2,  1),( 2, -1),( 1, -2),
-       (-1, -2),(-2, -1),(-2,  1),(-1,  2)).map(add_pair(x))
-
-def legal_moves(dim: Int, path: Path, x: Pos): List[Pos] = 
-  moves(x).filter(is_legal(dim, path))
-
-
-def ordered_moves(dim: Int, path: Path, x: Pos): List[Pos] = 
-  legal_moves(dim, path, x).sortBy((x) => (legal_moves(dim, path, x).length, dist(dim, x)))
-
-
-//moves(8)(1,3)
-//ordered_moves(8)(Nil)(1,3)
-//ordered_moves(8)(List((2, 4), (2, 6)))(1,3)
-
-
-
-def count_tours(dim: Int, path: Path): Int = {
-  if (path.length == dim * dim) 1
-  else 
-    (for (x <- legal_moves(dim, path, path.head)) yield count_tours(dim, x::path)).sum
-}
-
-def enum_tours(dim: Int, path: Path): List[Path] = {
-  if (path.length == dim * dim) List(path)
-  else 
-    (for (x <- legal_moves(dim, path, path.head)) yield enum_tours(dim, x::path)).flatten
-}
-
-def count_all_tours(dim: Int): Int = {
-  (for (i <- (0 until dim).toList; 
-        j <- (0 until dim).toList) yield count_tours(dim, List((i, j)))).sum
-}
-
-def enum_all_tours(dim: Int): List[Path] = {
-  (for (i <- (0 until dim).toList; 
-        j <- (0 until dim).toList) yield enum_tours(dim, List((i, j)))).flatten
-}
-
-/*
-for (dim <- 1 to 5) {
-  println(s"${dim} x ${dim} " + count_all_tours(dim))
-}
-
-for (dim <- 1 to 5) {
-  val ts = enum_all_tours(dim)
-  println(s"${dim} x ${dim} " + (if (ts == Nil) "" else { print_board(dim, ts.head) ; "" }))
-}
-*/
-
-
-def first(xs: List[Pos], f: Pos => Option[Path]): Option[Path] = xs match {
-  case Nil => None
-  case x::xs => {
-    val result = f(x)
-    if (result.isDefined) result else first(xs, f)
-  }
-}
-
-
-
-def first_tour(dim: Int, path: Path): Option[Path] = {
-  if (path.length == dim * dim) Some(path)
-  else
-    first(legal_moves(dim, path, path.head), (x: Pos) => first_tour(dim, x::path))
-}
-
-for (dim <- 1 to 8) {
-  val t = first_tour(dim, List((0, 0)))
-  println(s"${dim} x ${dim} " + (if (t == None) "" else { print_board(dim, t.get) ; "" }))
-}
- 
-
-/*
-def first2[A, B](xs: List[A], f: A => Option[B]): Option[B] =
-  xs.par.flatMap(f(_)).headOption
-*/
-
-def first_closed_tour_heuristics(dim: Int, path: Path): Option[Path] = {
-  if (path.length == dim * dim && moves(path.head).contains(path.last)) Some(path)
-  else
-    first(ordered_moves(dim, path, path.head), (x: Pos) => first_closed_tour_heuristics(dim, x::path))
-}
-
- 
-for (dim <- 1 to 6) {
-  val t = first_closed_tour_heuristics(dim, List((dim / 2, dim / 2)))
-  println(s"${dim} x ${dim} closed: " + (if (t == None) "" else { print_board(dim, t.get) ; "" }))
-}
-
-
-def first_tour_heuristics(dim: Int, path: Path): Option[Path] = {
-  if (path.length == dim * dim) Some(path)
-  else
-    first(ordered_moves(dim, path, path.head), (x: Pos) => first_tour_heuristics(dim, x::path))
-}
-
-/*
-for (dim <- 1 to 50) {
-  val t = first_tour_heuristics(dim, List((dim / 2, dim / 2)))
-  println(s"${dim} x ${dim}: " + (if (t == None) "" else { print_board(dim, t.get) ; "" }))
-}
-*/
-

--- a/progs/lecture1.scala	Wed Nov 16 14:37:18 2016 +0000
+++ b/progs/lecture1.scala	Wed Nov 16 15:05:40 2016 +0000
@@ -1,5 +1,5 @@
-// Lecture 1
-//===========
+// Scala Lecture 1
+//=================
 
 // Value assignments
 // (variable names should be lower case)

--- a/progs/lecture2.scala	Wed Nov 16 14:37:18 2016 +0000
+++ b/progs/lecture2.scala	Wed Nov 16 15:05:40 2016 +0000
@@ -1,3 +1,20 @@
+// Scala Lecture 2
+//=================
+
+
+// Option type
+//=============
+val lst = List(None, Some(1), Some(2), None, Some(3))
+
+lst.flatten
+Some(1).get
+
+val ps = List((3, 0), (3, 2), (4, 2), (2, 0), (1, 0), (1, 1))
+
+for ((x, y) <- ps) yield {
+  if (y == 0) None else Some(x / y)
+}
+
 // sudoku
 // some none
 // pattern matching