P91

(load "@lib/simul.l")

(grid 8 8)

# Generate legal moves for a given position
(de moves (Tour)
   (extract
      '((Jump)
         (let? Pos (Jump (car Tour))
            (unless (memq Pos Tour)
               Pos ) ) )
      (quote  # (taken from "games/chess.l")
         ((This) (: 0 1  1  0 -1  1  0 -1  1))        # South Southwest
         ((This) (: 0 1  1  0 -1  1  0  1  1))        # West Southwest
         ((This) (: 0 1  1  0 -1 -1  0  1  1))        # West Northwest
         ((This) (: 0 1  1  0 -1 -1  0 -1 -1))        # North Northwest
         ((This) (: 0 1 -1  0 -1 -1  0 -1 -1))        # North Northeast
         ((This) (: 0 1 -1  0 -1 -1  0  1 -1))        # East Northeast
         ((This) (: 0 1 -1  0 -1  1  0  1 -1))        # East Southeast
         ((This) (: 0 1 -1  0 -1  1  0 -1  1)) ) ) )  # South Southeast

# Build a list of moves, using Warnsdorff’s algorithm
: (let Tour '(b1)  # Start at b1
   (while
      (mini
         '((P) (length (moves (cons P Tour))))
         (moves Tour) )
      (push 'Tour @) )
   (flip Tour) )
-> (b1 a3 b5 a7 c8 b6 a8 c7 a6 b8 d7 f8 h7 g5 h3 g1 e2 c1 a2 b4 c2 a1 b3 a5 b7 d8 c6 d4 e6 c5 a4 c3 d1 b2 c4 d2 f1 h2 f3 e1 d3 e5 f7 h8 g6 h4 g2 f4 d5 e7 g8 h6 g4 e3 f5 d6 e8 g7 h5 f6 e4 g3 h1 f2)

http://picolisp.com/wiki/?99p91

31may11

abu