--- a/progs/knight2.scala	Thu Nov 03 01:05:20 2016 +0000
+++ b/progs/knight2.scala	Sat Nov 05 17:11:47 2016 +0000
@@ -26,7 +26,7 @@
 
 // non-circle tours
 def tour(n: Int)(steps: List[Pos]): List[List[Pos]] = {
-  if (steps.length ==  n * n) 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
 }
@@ -35,4 +35,5 @@
 val n = 6
 println(s"number simple tours: n = $n")
 
-println((for (i <- 0 until n; j <- 0 until n) yield tour(n)(List((i, j)))).flatten.distinct.size) 
+println(tour(n)(List((1,1))).distinct.size)
+//println((for (i <- 0 until n; j <- 0 until n) yield tour(n)(List((i, j)))).flatten.distinct.size) 

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/lecture1.scala	Sat Nov 05 17:11:47 2016 +0000
@@ -0,0 +1,9 @@
+// toList, toSet, toDouble
+// function definition
+// smart strings
+// maps
+// recursion
+// webpages
+
+
+

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/lecture2.scala	Sat Nov 05 17:11:47 2016 +0000
@@ -0,0 +1,1 @@
+// sudoku

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/lecture3.scala	Sat Nov 05 17:11:47 2016 +0000
@@ -0,0 +1,2 @@
+// regular expressions
+// ?? polymorphism

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/trade.scala	Sat Nov 05 17:11:47 2016 +0000
@@ -0,0 +1,66 @@
+
+
+val trades = List(28.0, 18.0, 20.0, 26.0, 24.0)
+
+def trade_times(xs: List[Double]): (Int, Int) = {
+  val low = xs.min
+  val low_index = xs.indexOf(low)
+  val rest = xs.drop(low_index)
+  val high = rest.max
+  val high_index = rest.indexOf(high)
+  (low_index, low_index + high_index)
+}
+
+
+trade_times(trades)
+
+assert(trade_times(List(10.0, 8.0, 7.0, 6.0)) == (3, 3), "the first test fails")
+
+
+
+import io.Source
+import scala.util._
+
+def get_page(url: String): List[String] = {
+  Try(Source.fromURL(url)("ISO-8859-1").getLines.toList).
+    getOrElse { println(s"  Problem with: $url"); List() }
+}
+
+def process_page(url: String): List[(String, Double)] = {
+  get_page(url).drop(1).map(_.split(",").toList).map((xs) => (xs(0), xs(6).toDouble))
+}
+
+def query_comp(name: String): (Int, Int) = {
+  val list = process_page("""http://ichart.yahoo.com/table.csv?s=""" + name)
+  trade_times(list.reverse.map(_._2))
+}
+
+
+val indices = List("GOOG", "AAPL", "MSFT", "IBM", "FB", "YHOO", "AMZN", "BIDU")
+
+indices.map(query_comp(_))
+
+val appl_page = get_page("""http://ichart.yahoo.com/table.csv?s=GOOG""")
+val goog_page = get_page("""http://ichart.yahoo.com/table.csv?s=GOOG""")
+goog_page.length
+
+val pairs = goog_page.drop(1).map(_.split(",").toList).map((xs:List[String]) => (xs(0), xs(6).toDouble))
+
+pairs.map(_._2)
+
+trade_times(pairs.reverse.map(_._2))
+
+pairs(3067)
+pairs(11)
+
+
+/*
+scala trade.scala 2> /dev/null || echo "command1 borked it"
+
+command1
+if [ $? -ne 0 ]; then
+    echo "command1 borked it"
+fi
+*/
+
+