advent-of-code-2023

commit 7d1af509cb7409b51302378d1e40a7e9416a38fc
parent 4cb0b879d1a96dd9a5afd45be2a80fcf631faeb4
Author: Lukas Henkel <lh@entf.net>
Date:   Sat,  2 Dec 2023 07:12:55 +0100

Don't use property lists for sets

Diffstat:
M
src/day-2.lisp
 | 
38
++++++++++++++++++++------------------

1 file changed, 20 insertions(+), 18 deletions(-)
diff --git a/src/day-2.lisp b/src/day-2.lisp
@@ -5,7 +5,9 @@
 
 (defun parse-sets (line start)
   (loop with sets = nil
-        with current-set = nil
+        with red = 0
+        with green = 0
+        with blue = 0
         for pos from start below (length line)
         do (multiple-value-bind (n end)
                (parse-integer line :start pos :junk-allowed t)
@@ -15,12 +17,15 @@
                                           (char= #\; char)))
                                     line
                                     :start pos))
-             (setf (getf current-set (make-keyword (upcase (subseq line (1+ pos) end)))) n
-                   pos (or end (1- (length line)))))
+             (ecase (aref line (1+ pos))
+               (#\r (setf red n))
+               (#\g (setf green n))
+               (#\b (setf blue n)))
+             (setf pos (or end (1- (length line)))))
         when (char= (aref line pos) #\;)
-          do (push current-set sets)
-          and do (setf current-set nil)
-        finally (return (cons current-set sets))))
+          do (push (list red green blue) sets)
+          and do (setf red 0 green 0 blue 0)
+        finally (return (cons (list red green blue) sets))))
 
 (defun parse-game-line (line)
   (let* ((start-game-id 5)
@@ -28,23 +33,20 @@
     (list (parse-integer line :start start-game-id :end end-game-id)
           (parse-sets line (1+ end-game-id)))))
 
+(defparameter *minimum-cubes* (list 12 13 14))
+
 (defun game-possible-p (sets)
   (loop for set in sets
-        for red = (getf set :red)
-        for green = (getf set :green)
-        for blue = (getf set :blue)
-        always (and (or (null red)
-                        (<= red 12))
-                    (or (null green)
-                        (<= green 13))
-                    (or (null blue)
-                        (<= blue 14)))))
+        always (loop for color-1 in set
+                     for color-2 in *minimum-cubes*
+                     always (<= color-1 color-2))))
 
 (defun game-power (sets)
   (apply #'*
-         (mapcar (lambda (color)
-                   (apply #'max (cons 0 (remove nil (mapcar (rcurry #'getf color) sets)))))
-                 (list :red :green :blue))))
+         (apply #'mapcar
+                (cons (lambda (&rest values)
+                        (apply #'max values))
+                      sets))))
 
 (defun day-2 (input)
   (loop for line = (read-line input nil)