tasks a-s

2013-04-10 23:57:08 -07:00 · 2013-04-10 23:57:08 -07:00 · b83f433714
commit b83f433714
parent 47bf37c096
12433 changed files with 156208 additions and 123 deletions
--- a/Task/N-queens-problem/Factor/n-queens-problem.factor
+++ b/Task/N-queens-problem/Factor/n-queens-problem.factor
@ -0,0 +1,27 @@
+USING: kernel sequences math math.combinatorics formatting io locals ;
+IN: queens
+
+: /=  ( x y -- ? )   = not ; inline
+
+:: safe?  ( board q -- ? )
+    [let  q board nth :> x
+      q iota [
+         x swap
+         [ board nth ] keep
+         q swap -
+           [ + /= ]
+           [ - /= ] 3bi and
+      ] all?
+    ] ;
+
+: solution? ( board -- ? )
+    dup length iota [ dupd safe? ] all? nip ;
+
+: queens ( n -- l )
+    iota all-permutations [ solution? ] filter ;
+
+: .queens ( n -- )
+    queens
+    [
+      [ 1 + "%d " printf ] each nl
+    ] each ;