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-rw-r--r--AoC2023/day13/solver.lisp85
1 files changed, 47 insertions, 38 deletions
diff --git a/AoC2023/day13/solver.lisp b/AoC2023/day13/solver.lisp
index f149f2e..53cc753 100644
--- a/AoC2023/day13/solver.lisp
+++ b/AoC2023/day13/solver.lisp
@@ -1,4 +1,7 @@
-(ql:quickload '(fiveam))
+;; 6:34
+;; 8:11 part 1
+;; 9:36 part 2
+(ql:quickload '(fiveam arrows cl-ppcre))
(defparameter eg-vert "#...##..#
#....#..#
@@ -16,26 +19,24 @@
..##..##.
#.#.##.#.")
-(defun find-repeat (rows)
- (loop for (one two-or-nil) on rows by #'cdr
- for idx from 0
- when (and (not (null two-or-nil))
- (equal one two-or-nil))
- collect (1+ idx)))
+(defun count-differences (a b)
+ (loop for x across a
+ for y across (or b "")
+ count (not (eq x y))))
-(defun find-v-mirror (rows)
- (remove-if-not (lambda (n) (v-mirror-p rows n))
- (find-repeat rows)))
+(defun v-mirror (rows &optional (max-differences 0))
+ (loop
+ for idx from 1 below (length rows)
+ when
+ (= max-differences
+ (loop
+ for above in (reverse (subseq rows 0 idx))
+ for below in (subseq rows idx)
+ sum (count-differences above below)))
+ do (return idx)))
-(defun v-mirror-p (rows idx)
- (every #'equal
- (reverse (subseq rows 0 idx))
- (subseq rows idx)))
-
-
-(defun find-h-mirror (rows)
- (find-v-mirror
- (transpose-rows rows)))
+(defun h-mirror (rows &optional (max-differences 0))
+ (v-mirror (transpose-rows rows) max-differences))
(defun transpose-rows (rows)
(arrows:-<>
@@ -46,30 +47,36 @@
(fiveam:test partials
(fiveam:is
- (equal '(4)
- (find-repeat
- (cl-ppcre:split "\\n" eg-vert))))(fiveam:is
- (equal '(4)
- (find-v-mirror
- (cl-ppcre:split "\\n" eg-vert))))
-
+ (= 4
+ (v-mirror
+ (cl-ppcre:split "\\n" eg-vert))))
(fiveam:is
- (equal '(3)
- (find-repeat
- (cl-ppcre:split "\\n" eg-horizontal))))
+ (= 1
+ (v-mirror
+ (cl-ppcre:split "\\n" eg-vert) 1)))
(fiveam:is
- (null (find-v-mirror
+ (null (v-mirror
(cl-ppcre:split "\\n" eg-horizontal))))
(fiveam:is
- (equal '(5)
- (find-h-mirror
- (cl-ppcre:split "\\n" eg-horizontal)))))
+ (= 3 (v-mirror
+ (cl-ppcre:split "\\n" eg-horizontal) 1)))
+ (fiveam:is
+ (= 5
+ (h-mirror
+ (cl-ppcre:split "\\n" eg-horizontal))))
+ (fiveam:is
+ (null (h-mirror
+ (cl-ppcre:split "\\n" eg-horizontal) 1))))
-(defun solver (maps)
- (let ((verical-mirrors (delete nil (mapcan #'find-v-mirror maps)))
- (horizontal-mirrors (delete nil (mapcan #'find-h-mirror maps))))
+(defun solver (maps &optional (max-differences 0))
+ (let ((vertical-mirrors (delete nil (mapcar (lambda (m)
+ (v-mirror m max-differences))
+ maps)))
+ (horizontal-mirrors (delete nil (mapcar (lambda (m)
+ (h-mirror m max-differences))
+ maps))))
(+
- (* 100 (apply #'+ verical-mirrors))
+ (* 100 (apply #'+ vertical-mirrors))
(apply #'+ horizontal-mirrors))))
(defun parse-input (file)
@@ -80,6 +87,8 @@
(fiveam:test solutions
(fiveam:is (= 405 (solver (parse-input "eg-in"))))
- (fiveam:is (= 35360 (solver (parse-input "input")))))
+ (fiveam:is (= 400 (solver (parse-input "eg-in") 1)))
+ (fiveam:is (= 35360 (solver (parse-input "input"))))
+ (fiveam:is (= 36755 (solver (parse-input "input") 1))))
(fiveam:run!)