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-rw-r--r--AoC2023/day16/solver.lisp40
1 files changed, 27 insertions, 13 deletions
diff --git a/AoC2023/day16/solver.lisp b/AoC2023/day16/solver.lisp
index 8b967a4..72abf43 100644
--- a/AoC2023/day16/solver.lisp
+++ b/AoC2023/day16/solver.lisp
@@ -1,7 +1,7 @@
;;8:57
;;10:26 part1
+;;10:53 part2
(ql:quickload '(fiveam arrows alexandria))
-(defparameter eg-in "")
(defun in-bounds (field ray)
(destructuring-bind (maxrow maxcol) (array-dimensions field)
@@ -71,23 +71,37 @@
(remove-if-not (alexandria:curry #'in-bounds field))
(remove-if (alexandria:curry #'energized-p energized)))))
-(defun advancer (field rays energized maxi)
+(defun advancer (field rays energized)
(loop for (dir row col) in rays do
(push dir (gethash (cons row col) energized)))
- (if (or (null rays) (> maxi 5000))
- energized
- (let ((next-moves (mapcan (lambda (ray) (action field ray energized)) rays)))
- ;; (format t "~d Next: ~a~%" maxi next-moves)
- (advancer field next-moves energized (1+ maxi)))))
+ (if (null rays)
+ energized
+ (let ((next-moves (mapcan (lambda (ray) (action field ray energized)) rays)))
+ ;; (format t "~d Next: ~a~%" maxi next-moves)
+ (advancer field next-moves energized))))
-(defun solver1 (input)
+(defun boundary-rays (field)
+ (destructuring-bind (maxrow maxcol) (array-dimensions field)
+ (append
+ (loop for i below maxrow collect (list 'rt i 0))
+ (loop for i below maxrow collect (list 'lf i (1- maxcol)))
+ (loop for i below maxcol collect (list 'dw 0 i))
+ (loop for i below maxcol collect (list 'up (1- maxrow) i)))))
+
+(defun solver (field)
+ (lambda (start)
+ (hash-table-count
+ (advancer field (list start)
+ (make-hash-table :test #'equal)))))
+
+(defun solution (input &optional (starter (constantly (list (list 'rt 0 0)))))
(let* ((rows (length input))
- (energized (make-hash-table :test #'equal))
(field
(make-array (list rows (length (car input))) :initial-contents input)))
- (advancer field (list (list 'rt 0 0)) energized 0)
- (hash-table-count energized)))
+ (reduce #'max (funcall starter field) :key (solver field))))
(fiveam:test solutions
- (fiveam:is (= 46 (solver1 (uiop:read-file-lines "eg-in"))))
- (fiveam:is (= 7996 (solver1 (uiop:read-file-lines "input")))))
+ (fiveam:is (= 46 (solution (uiop:read-file-lines "eg-in"))))
+ (fiveam:is (= 7996 (solution (uiop:read-file-lines "input"))))
+ (fiveam:is (= 51 (solution (uiop:read-file-lines "eg-in") #'boundary-rays)))
+ (fiveam:is (= 8239 (solution (uiop:read-file-lines "input") #'boundary-rays))))