bfs.lisp

(defun make-random-bitarray (n)
  "Generate a random list of bits of length N"
  (let ((arr nil)
	(i 0))
    (loop while (not (eq i n)) do
	 (progn (incf i 1) (push (random 2) arr)))
    arr))

(defun make-random-adj-mat (n)
  "Generate a random adjacency matrix (for a digraph) of size n"
  (let ((mat nil)
	(i 0))
    (loop while (not (eq i n)) do
	 (progn  (incf i 1) (push (make-random-bitarray n) mat)))
    mat))

;; Generate graphs using (make-dot-from-mat (make-random-bitarray <size>) <filename>)
(defun make-dot-from-mat (mat filename)
  (let ((i 0)
	(j 0)
	(out (open filename :direction :output :if-does-not-exist :create)))
    (write-line "digraph {" out)
    (dolist (arr mat)
      (dolist (bit arr)
	(unless (eq 0 bit)
	  (write-line (format nil "~a -> ~a [];" i j) out))
	(incf j 1))
      (incf i 1)
      (setq j 0))
    (write-line "}" out)
    (close out)))

1. A random bit array of size N is a random number up to 2**n converted to bits.
2. Use the dotimes macro .