commit - eba1e3d671fb248cdf9966ced55805a490815e97
commit + 1fa917d31e78f7342ab690a3447ef3ac47c9fcd9
blob - f0d5a9b73d6e912c8d560a3da97b4a36f2cbe8dd
blob + 3f2e32ac03000d00d324942cefd318799af44ddc
--- src/day-5.lisp
+++ src/day-5.lisp
(uiop:split-string line :separator '(#\|))))
(defun parse-update (line)
- (map 'vector
- #'parse-integer
- (uiop:split-string line :separator '(#\,))))
+ (mapcar #'parse-integer
+ (uiop:split-string line :separator '(#\,))))
-(defun update-ordered-p (update rules)
- (loop for (first second) in rules
- for pos-first = (position first update)
- for pos-second = (position second update)
- unless (or
- (null pos-first)
- (null pos-second)
- (< pos-first pos-second))
- do (return nil)
- finally (return t)))
-
(defun order-update (update rule-map)
(sort update (lambda (first second)
(not (gethash (list second first) rule-map)))))
(defun middle-page-number (update)
- (aref update (floor (length update) 2)))
+ (nth (floor (length update) 2) update))
(defun day-5 (input)
- (loop with rules = nil
- with rule-map = (make-hash-table :test #'equal)
+ (loop with rule-map = (make-hash-table :test #'equal)
with processing-updates = nil
with task-1 = 0
with task-2 = 0
until (null line)
do (cond
(processing-updates
- (let ((update (parse-update line)))
- (if (update-ordered-p update rules)
- (incf task-1 (middle-page-number update))
- (progn
- (setf update (order-update update rule-map))
- (incf task-2 (middle-page-number update))))))
+ (let* ((update (parse-update line))
+ (sorted (order-update (copy-seq update) rule-map))
+ (middle (middle-page-number sorted)))
+ (if (seq= update sorted)
+ (incf task-1 middle)
+ (incf task-2 middle))))
((string= line "")
(setf processing-updates t))
- (t (let ((rule (parse-rule line)))
- (setf (gethash rule rule-map) t)
- (push rule rules))))
+ (t (setf (gethash (parse-rule line) rule-map) t)))
finally (return (values task-1 task-2))))
