diff -r 9b5165b8a762 -r 0587ef444547 progs/knight5.scala
--- a/progs/knight5.scala	Sat Mar 11 23:12:49 2023 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,45 +0,0 @@
-import scala.util._
-
-def print_board(n: Int)(steps: List[(Int, Int)]): Unit = synchronized {
-  for (i <- 0 until n) {
-    for (j <- 0 until n) {
-      print(f"${steps.indexOf((i, j))}%3.0f ")
-    }
-    println
-  } 
-  //readLine()
-  System.exit(0)
-}
-
-def add_pair(x: (Int, Int))(y: (Int, Int)) = 
-  (x._1 + y._1, x._2 + y._2)
-
-def is_legal(n: Int)(x: (Int, Int)) = 
-  0 <= x._1 && 0 <= x._2 && x._1 < n && x._2 < n
-
-def moves(n: Int)(x: (Int, Int)): List[(Int, Int)] = {
-  List((1, 2),(2, 1),(2, -1),(1, -2),
-       (-1, -2),(-2, -1),(-2, 1),(-1, 2)).map(add_pair(x)).filter(is_legal(n))
-}
-
-def ordered_moves(n: Int)(steps: List[(Int, Int)])(x : (Int, Int)): List[(Int, Int)] = 
-  moves(n)(x).sortBy((x: (Int, Int)) => moves(n)(x).filterNot(steps.contains(_)).length)
-
-moves(8)(1,3)
-ordered_moves(8)(Nil)(1,3)
-ordered_moves(8)(List((2, 4), (2, 6)))(1,3)
-
-// non-circle tour parallel
-def tour(n: Int)(steps: List[(Int, Int)]): Unit = {
-  if (steps.length ==  n * n) // && moves(n)(steps.head).contains(steps.last))
-    print_board(n)(steps)
-  else 
-    for (x <- ordered_moves(n)(steps)(steps.head); if (!steps.contains(x))) tour(n)(x :: steps)
-}
-
-val n = 21
-println(s"circle tour parallel fast: n = $n")
-
-val starts = for (i <- 0 until n; j <- 0 until n) yield (i, j)
-
-starts.par.foreach((x:(Int, Int)) => tour(n)(List(x)))