Arc Forum | Good idea. But "(nil! m)" gives me an error. After making the other changes yo...

Arc Forum

1 point by map 6137 days ago | link | parent

Good idea. But "(nil! m)" gives me an error. After making the other changes you suggested, it occurred to me to combine the two "if" clauses into one.

  (def rot ((x . y)) (join y `(,x)))
  (def nqueens (n)
    (withs (r (range 1 n) o (keep odd r) e (keep even r) m (mod n 12))
      (join (if (pos m '(3 9))(or wipe.m rot.e) e)
        (case m
          2 (flat:list 3 1 (cut o 3 -1) 5)
          8 (flat:map rev pair.o)
          nil (rot:rot o)
          o))))

Edit: used "wipe" as suggested below.

Edit: using "flat:list" for case 2.

Edit: replaced (wipe m) with wipe.m, etc.