Binary file cws/cw02.pdf has changed

--- a/cws/cw02.tex	Fri Nov 11 16:44:19 2016 +0000
+++ b/cws/cw02.tex	Sat Nov 12 15:20:56 2016 +0000
@@ -1,8 +1,7 @@
 \documentclass{article}
-\usepackage{../style}
 \usepackage{chessboard}
 \usepackage[LSBC4,T1]{fontenc}
-
+\usepackage{../style}
 
 \begin{document}
 
@@ -16,12 +15,24 @@
 
 \section*{Coursework 7 (Scala, Knight's Tour)}
 
-This coursework is worth 10\% and is due on 21 November at 11pm. You
-are asked to implement a Scala program that solves the \textit{knight's
-  tour problem} on an $n\times n$ chessboard. This problem is about
-finding a tour such that the knight visits every field on the
-chessboard once. One a $5\times 5$ chessboard, a knight's tour
-is as follows:
+This coursework is worth 10\%. The first part is due on 23 November
+at 11pm; the second, more advanced part, is due on 30 November at
+11pm. You are asked to implement Scala programs that solve various
+versions of the \textit{Knight's Tour Problem} on a chessboard.
+ 
+\subsection*{Disclaimer}
+
+It should be understood that the work you submit represents
+your own effort. You have not copied from anyone else. An
+exception is the Scala code I showed during the lectures or
+uploaded to KEATS, which you can freely use.\bigskip
+
+\subsection*{Background}
+
+The \textit{Knight's Tour Problem} is about finding a tour such that
+the knight visits every field on a $n\times n$ chessboard once. For
+example on a $5\times 5$ chessboard, a knight's tour is as follows:
+
 
 \chessboard[maxfield=e5, 
             pgfstyle= {[base,at={\pgfpoint{0pt}{-0.5ex}}]text},
@@ -53,18 +64,23 @@
            ]
 
 \noindent
-The tour starts in the left-upper corner, then moves to field $(4,3)$,
-then $(5,1)$ and so on. A knight's tour is called \emph{closed}, if
+The tour starts in the right-upper corner, then moves to field $(4,3)$,
+then $(5,1)$ and so on. There are no knight's tours on $2\times 2$, $3\times 3$
+and $4\times 4$ chessboards, but for every bigger board there is.
+
+
+A knight's tour is called \emph{closed}, if
 the last step in the tour is within a knight's move to the beginning
-of the tour. So the above knight's tour is not closed (that is it is
+of the tour. So the above knight's tour is \underline{not} closed (it is
 open) because the last step on field $(1, 5)$ is not within the reach
 of the first step on $(5, 5)$. It turns out there is no closed
-knight's tour on a $5\times 5$ board. But there is one on a $6\times
-6$ board.
+knight's tour on a $5\times 5$ board. But there are on a $6\times
+6$ board.\bigskip
 
-If you cannot remember how a knight moved in chess, below are all
-potential moves indicated for two knights, one on field $(3, 3)$ and
-another on $(8, 8)$:
+\noindent
+If you cannot remember how a knight moved in chess, or never played
+chess, below are all potential moves indicated for two knights, one on
+field $(3, 3)$ and another on $(8, 8)$:
 
 
 \chessboard[color=blue!50,
@@ -78,12 +94,6 @@
             setpieces={Nh8, Nc3}]
 
 
-\subsubsection*{Disclaimer}
-
-It should be understood that the work you submit represents
-your own effort. You have not copied from anyone else. An
-exception is the Scala code I showed during the lectures or
-uploaded to KEATS, which you can freely use.\bigskip
 
 
 \subsubsection*{Task}

Binary file progs/collatz.scala has changed

--- a/progs/drumb.scala	Fri Nov 11 16:44:19 2016 +0000
+++ b/progs/drumb.scala	Sat Nov 12 15:20:56 2016 +0000
@@ -1,4 +1,4 @@
-// Advanvced Part 3 about really dump investing strategy
+// Advanvced Part 3 about really dumb investing strategy
 //=======================================================
 
 //two test portfolios

--- a/progs/drumb_sol.scala	Fri Nov 11 16:44:19 2016 +0000
+++ b/progs/drumb_sol.scala	Sat Nov 12 15:20:56 2016 +0000
@@ -1,4 +1,4 @@
-// Advanvced Part 3 about really dump investing strategy
+// Advanvced Part 3 about really dumb investing strategy
 //=======================================================
 
 //two test portfolios

--- a/progs/knight2.scala	Fri Nov 11 16:44:19 2016 +0000
+++ b/progs/knight2.scala	Sat Nov 12 15:20:56 2016 +0000
@@ -26,9 +26,11 @@
 
 // non-circle tours
 def tour(n: Int)(steps: List[Pos]): List[List[Pos]] = {
-  if (steps.length ==  n * n && moves(n)(steps.head).contains(steps.last)) List(steps)
+  if (steps.length ==  n * n) // && moves(n)(steps.head).contains(steps.last)) 
+    List(steps)
   else 
-    (for (x <- moves(n)(steps.head).par; if (!steps.contains(x))) yield tour(n)(x :: steps)).toList.flatten
+    (for (x <- moves(n)(steps.head).par; 
+          if (!steps.contains(x))) yield tour(n)(x :: steps)).toList.flatten
 }
 
 //val n = 8

--- a/progs/lecture2.scala	Fri Nov 11 16:44:19 2016 +0000
+++ b/progs/lecture2.scala	Sat Nov 12 15:20:56 2016 +0000
@@ -2,6 +2,11 @@
 // some none
 // pattern matching
 
+//type abbreviations
+type Pos = (int, Int)
+
+//sorting, higher-order functions
+//lexicographic ordering
 
 
 // Implicits