refactor because

1 files changed, 9 insertions, 12 deletions

diff --git a/AoC2022/12/solver.lisp b/AoC2022/12/solver.lisp
index e0320c3..f4fd602 100644
--- a/AoC2022/12/solver.lisp
+++ b/AoC2022/12/solver.lisp
@@ -28,22 +28,20 @@
     (make-land :elevation (map 'vector #'elevation (apply #'concatenate 'string data))
                :neighbors (possible-directions (length (car data)) (length data)))))
 
-(defun appropriate (place elevation land paths)
+(defun appropriate (place current land paths)
   (and (not (gethash place paths)) ;; not visited
-       (>= elevation (aref (land-elevation land) place))))
+       (>= 1 (- (aref (land-elevation land) place)
+                (aref (land-elevation land) current)))
+       (setf (gethash place paths) (cons place (gethash current paths)))))
 
 (defun next-steps (place land paths)
-  (let ((elevation (aref (land-elevation land) place)))
-    (unless (= 27 elevation)
-      (loop :for option :in (funcall (land-neighbors land) place)
-            :when (appropriate option (1+ elevation) land paths)
-              :do (setf (gethash option paths) (cons option (gethash place paths)))
-              :and collect option))))
+  (remove-if-not (lambda (option) (appropriate option place land paths))
+                 (funcall (land-neighbors land) place)))
 
 (defun shortest-path (starts land paths)
-  (let ((next (mapcan (lambda (place) (next-steps place land paths)) starts)))
-    (when next
-      (shortest-path next land paths))))
+  (unless (null starts)
+    (shortest-path (append (cdr starts) (next-steps (car starts) land paths))
+                   land paths)))
 
 (defun solver (input-file start-p)
   (let* ((land (land input-file))
@@ -62,5 +60,4 @@
   (fiveam:is (= 29 (solver "eg-in" (lambda (x) (<= x 1)))))
   (fiveam:is (= 361 (solver "input" (lambda (x) (= x 0)))))
   (fiveam:is (= 354 (solver "input" (lambda (x) (<= x 1))))))
-
 (fiveam:run-all-tests)