Sudoku: Difference between revisions

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@@ Line 104: / Line 104: @@
   (let* ((rmin (* 3 (floor row 3)))    (rmax (+ rmin 3))
          (cmin (* 3 (floor column 3))) (cmax (+ cmin 3)))
-    (do ((r rmin (1+ r))) ((eql r rmax) neighbors)
+    (do ((r rmin (1+ r))) ((= r rmax) neighbors)
-      (do ((c cmin (1+ c))) ((eql c cmax))
+      (do ((c cmin (1+ c))) ((= c cmax))
         (let ((x (aref grid r c)))
           (unless (or (eq x '_) (= r row) (= c column))
@@ Line 119: / Line 119: @@
 (defun solve (grid &optional (row 0) (column 0))
   (cond
-   ((eql row 9)
+   ((= row 9)
     grid)
-   ((eql column 9)
+   ((= column 9)
     (solve grid (1+ row) 0))
-   ((numberp (aref grid row column))
+   ((not (eq '_ (aref grid row column)))
     (solve grid row (1+ column)))
    (t (dolist (choice (choices row column grid) (setf (aref grid row column) '_))