part2

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))))