--- a/progs/lecture4.scala	Fri Dec 02 07:48:03 2022 +0000
+++ b/progs/lecture4.scala	Fri Dec 02 11:05:41 2022 +0000
@@ -280,7 +280,7 @@
 // Tail recursion
 //================
 
-def fact(n: BigInt): BigInt = 
+def fact(n: Int): Int = 
   if (n == 0) 1 else n * fact(n - 1)
 
 

--- a/progs/sudoku.scala	Fri Dec 02 07:48:03 2022 +0000
+++ b/progs/sudoku.scala	Fri Dec 02 11:05:41 2022 +0000
@@ -52,6 +52,7 @@
 def candidates(game: String, pos: Pos): List[Char] = 
   allValues.diff(toAvoid(game, pos))
 
+
 def search(game: String): List[String] = {
   if (isDone(game)) List(game)
   else 
@@ -59,6 +60,8 @@
       map(c => search(update(game, empty(game), c))).toList.flatten
 }
 
+
+
 def search1T(games: List[String]): Option[String] = games match {
   case Nil => None
   case game::rest => {
@@ -201,7 +204,7 @@
 
 
 val total = 
-  (for ((game, i) <- hard_games.zipWithIndex.par) yield {
+  (for ((game, i) <- hard_games.zipWithIndex) yield {
     val secs = time_needed(1, search(game))
     println(f"${i}%2.0f: ${game} |${secs}%2.3f secs")
     secs