Sudoku: Difference between revisions

(let* ((rmin (* 3 (floor row 3))) (rmax (+ rmin 3))

(cmin (* 3 (floor column 3))) (cmax (+ cmin 3)))

(let ((x (aref grid r c)))

(unless (or (eq x '_) (= r row) (= c column))

(defun solve (grid &optional (row 0) (column 0))

(cond

grid)

(solve grid (1+ row) 0))

(solve grid row (1+ column)))

(t (dolist (choice (choices row column grid) (setf (aref grid row column) '_))