;;; -*- Mode:LISP; Package:LISP-INTERNALS; Readtable:CL; Base:10 -*-

(defvar *board*)
(defvar *sequence*)
(defvar *a*)
(defvar *b*)
(defvar *c*)
(defvar *answer*)
(defvar *final*)

(defun setup-triang ()
  (setq *board* (make-array 16.))
  (dotimes (i 16.) (setf (svref *board* i) 1))
  (setq *sequence* (make-array 14.))
  (dotimes (i 14.) (setf (svref *sequence* i) 0))
  (setq *a* (make-array 37.))
  (setq *b* (make-array 37.))
  (setq *c* (make-array 37.))
  (do ((i 0 (1+ i))
       (aa '(1 2 4 3 5 6 1 3 6 2 5 4 11 12 13 7 8 4 4 7 11 8 12 13 6 10 15 9 14 13 13 14 15 9 10 6) (cdr aa))
       (bb '(2 4 7 5 8 9 3 6 10 5 9 8 12 13 14 8 9 5 2 4 7 5 8 9 3 6 10 5 9 8 12 13 14 8 9 5) (cdr bb))
       (cc '(4 7 11 8 12 13 6 10 15 9 14 13 13 14 15 9 10 6 1 2 4 3 5 6 1 3 6 2 5 4 11 12 13 7 8 4) (cdr cc)))
      ((= i 37.))
    (setf (aref *a* i) (car aa))
    (setf (aref *b* i) (car bb))
    (setf (aref *c* i) (car cc)))
  (setf (aref *board* 5) 0))

(defun last-position ()
       (do ((i 1 (1+ i)))
	   ((= i 16.) 0)
	   (cond ((= 1 (aref *board* i)) (return i)))))

(defun try (i depth)
       (cond ((= depth 14) 
	      (let ((lp (last-position)))
		   (unless (member lp *final*)
			 (push lp *final*)))
	      (push (cdr (map 'list #'quote *sequence*)) *answer*)
	      t)
	     ((and (= 1 (aref *board* (aref *a* i)))
		   (= 1 (aref *board* (aref *b* i)))
		   (= 0 (aref *board* (aref *c* i))))
	      (setf (aref *board* (aref *a* i)) 0)
	      (setf (aref *board* (aref *b* i)) 0)
	      (setf (aref *board* (aref *c* i)) 1)
	      (setf (aref *sequence* depth) i)
	      (do ((j 0 (1+ j))
		   (depth (1+ depth)))
		  ((or (= j 36.)
		       (try j depth)) ()))
	      (setf (aref *board* (aref *a* i)) 1)
	      (setf (aref *board* (aref *b* i)) 1)
	      (setf (aref *board* (aref *c* i)) 0)())))

(defun gogogo (i)
       (let ((*answer* ())
	     (*final* ()))
	    (try i 1)))

(defun quote (x)
  (cons 'quote x))

(defun test-triang ()
  (boot-stack-groups)
  (setup-triang)
  (hw:write-microsecond-clock (hw:unboxed-constant 0))
  (error "TRIANG" (gogogo 22.) (hw:read-microsecond-clock))
  (loop))