diff options
| -rw-r--r-- | AoC2023/day10/solver.lisp | 27 |
1 files changed, 13 insertions, 14 deletions
diff --git a/AoC2023/day10/solver.lisp b/AoC2023/day10/solver.lisp index d93617a..11bd41c 100644 --- a/AoC2023/day10/solver.lisp +++ b/AoC2023/day10/solver.lisp @@ -71,20 +71,22 @@ LJ.LJ") (let* ((start (find-start map)) (options (start-neighbors map start)) (last start) - (cur (car options))) - (cons cur - (loop - for next = (advance-next map cur last) - do (setf last cur - cur next) - collect next - until (equal next start))))) + (cur (car options)) + (loop-tiles (make-hash-table :test #'equal))) + (setf (gethash cur loop-tiles) t) + (loop + for next = (advance-next map cur last) + do (setf last cur + cur next + (gethash next loop-tiles) t) + until (equal next start)) + loop-tiles)) ;; (get-loop ;; (uiop:split-string eg-input :separator '(#\Newline))) (defun solver1 (rows) (let ((map (make-array (length rows) :initial-contents rows))) - (floor (length (get-loop map)) 2))) + (floor (hash-table-count (get-loop map)) 2))) ;; To know if a point is inside a loop, I need to count how often a ray crosses ;; until it reaches the boundary. I can just count to the right. @@ -93,9 +95,6 @@ LJ.LJ") ;; those 2 cells taking the point a bit lower, would mean only counting pipes ;; with down component thus F,|,7. The rest L,-,J are irrelevant. -(defun in-loop-p (point loop) - (member point loop :test #'equal)) - (defun rassoc-get (item list) (car (rassoc item list :test #'equal))) @@ -122,10 +121,10 @@ LJ.LJ") (loop for col across row for x from 0 for point = (list y x) - when (and (in-loop-p point loop-tiles) + when (and (gethash point loop-tiles) (member col '(#\F #\| #\7))) do (setf insidep (not insidep)) - count (and (not (in-loop-p point loop-tiles)) + count (and (not (gethash point loop-tiles)) insidep))))) (fiveam:test solution |