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authorOscar Najera <hi@oscarnajera.com>2023-12-04 18:37:20 +0100
committerOscar Najera <hi@oscarnajera.com>2023-12-04 18:37:20 +0100
commit6e2e487e8c87102c2761986cc8b7941290d0a2db (patch)
tree8b543600288d59faf8d7e6b6d9556b7d42fdf8f6 /AoC2023/day04
parentb43f2a47e83aa7ca9c8144e3f144d2c69c7fc579 (diff)
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Solve day04 part2
Diffstat (limited to 'AoC2023/day04')
-rw-r--r--AoC2023/day04/solver.lisp34
1 files changed, 31 insertions, 3 deletions
diff --git a/AoC2023/day04/solver.lisp b/AoC2023/day04/solver.lisp
index ec8f09d..2baed03 100644
--- a/AoC2023/day04/solver.lisp
+++ b/AoC2023/day04/solver.lisp
@@ -1,4 +1,4 @@
-(ql:quickload '(fiveam str transducers))
+(ql:quickload '(fiveam str arrows transducers))
(defpackage #:day04
(:use #:cl #:fiveam)
@@ -28,10 +28,38 @@ Card 6: 31 18 13 56 72 | 74 77 10 23 35 67 36 11")
(t:comp
(t:filter-map #'matching-numbers)
(t:map #'length)
- (t:map (lambda (n) (expt 2 (1- n)))))
+ (t:map #'1-)
+ (t:map (lambda (n) (expt 2 n))))
#'+
lines))
+(defun solver1c (lines)
+ (arrows:->>
+ (mapcar #'matching-numbers lines)
+ (remove-if #'null)
+ (mapcar #'length)
+ (mapcar #'1-)
+ (mapcar (lambda (n) (expt 2 n)))
+ (apply #'+)))
+
+(defun solver2 (lines)
+ (let* ((line-count (length lines))
+ (stash (make-hash-table :size line-count)))
+ (loop
+ for line in lines
+ for i from 0
+ for matches = (length (matching-numbers line))
+ do (incf (gethash i stash 0))
+ (dotimes (j matches)
+ (when (< (+ i j 1) line-count)
+ (incf (gethash (+ i j 1) stash 0)
+ (gethash i stash))))
+ sum (gethash i stash 0))))
+
(test solutions
(is (= 13 (solver1 (uiop:split-string eg-input :separator '(#\Newline)))))
- (is (= 18619 (solver1 #p"input"))))
+ (is (= 13 (solver1c (uiop:split-string eg-input :separator '(#\Newline)))))
+ (is (= 18619 (solver1 #p"input")))
+ (is (= 18619 (solver1c (uiop:read-file-lines "input"))))
+ (is (= 30 (solver2 (uiop:split-string eg-input :separator '(#\Newline)))))
+ (is (= 8063216 (solver2 (uiop:read-file-lines "input")))))