From 2d8ad6ddcce3421b3a94805e568c02b644989927 Mon Sep 17 00:00:00 2001
From: Oscar Najera <hi@oscarnajera.com>
Date: Fri, 15 Dec 2023 19:29:51 +0100
Subject: [AoC2023] day12 part1 lisp

---
 AoC2023/day12/solver.lisp | 72 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 46 insertions(+), 26 deletions(-)

diff --git a/AoC2023/day12/solver.lisp b/AoC2023/day12/solver.lisp
index ce196c9..c93a351 100644
--- a/AoC2023/day12/solver.lisp
+++ b/AoC2023/day12/solver.lisp
@@ -11,30 +11,50 @@
 ????.######..#####. 1,6,5
 ?###???????? 3,2,1")
 
+(defun parse-line (line)
+  (destructuring-bind (row . damage-list)
+      (cl-ppcre:split "[\\s,]" line)
+    (cons row (mapcar #'parse-integer damage-list))))
 
-(destructuring-bind (row . damage-list)
-    (cl-ppcre:split "[\\s,]" "???.###. 1,1,3")
-  (setf damage-list (mapcar #'parse-integer damage-list))
-  (labels ((options (row-idx damage-group)
-             (cond
-               ;; commited to all options
-               ((= damage-group (length damage-list))
-                ;; If still damaged springs are left, then
-                ;; it was a wrong arrangement, otherwise counts
-                (if (find damaged (subseq row row-idx)) 0 1))
-               ;; Not enough space to fit the current damaged-group
-               ((<= (length row) (+ row-idx (elt damage-list damage-group))) 0)
-               ;; Probe options. Either commit to a damage-group at row-idx or skip position
-               (t
-                (let* ((damaged-count (elt damage-list damage-group))
-                       (next-slot (+ row-idx damaged-count)))
-                  (+ (if (not (or (find operational (subseq row row-idx next-slot))
-                                  (char-equal damaged (aref row next-slot))))
-                         ;; commits to the damage group, because in condition it has space
-                         ;; Skips one slot, because it checked that it wasn't damaged
-                         (options (1+ next-slot) (1+ damage-group))
-                         0)
-                     (if (not (char-equal damaged (aref row row-idx)))
-                         (options (1+ row-idx) damage-group)
-                         0)))))))
-    (options 0 0)))
+(defun solve-row (line)
+  (destructuring-bind (row . damage-list) (parse-line line)
+    (labels ((options (row-idx damage-group)
+               (cond
+                 ;; commited to all options
+                 ((= damage-group (length damage-list))
+                  ;; If commited to all slots too, is valid option
+                  ;; If still damaged springs are left, then
+                  ;; it was a wrong arrangement, otherwise counts
+                  (cond ((>= row-idx (length row)) 1)
+                        ((find damaged (subseq row row-idx)) 0)
+                        (1)))
+                 ;; Not enough space to fit the current damaged-group
+                 ((< (length row) (+ row-idx (elt damage-list damage-group))) 0)
+                 ;; Probe options. Either commit to a damage-group at row-idx or skip position
+                 (t
+                  (let* ((damaged-count (elt damage-list damage-group))
+                         (next-slot (+ row-idx damaged-count)))
+                    (+ (if (not (or (find operational (subseq row row-idx next-slot))
+                                    (and (< next-slot (length row))
+                                         (char-equal damaged (aref row next-slot)))))
+                           ;; commits to the damage group, because in condition it has space
+                           ;; Skips one slot, because it checked that it wasn't damaged
+                           (options (1+ next-slot) (1+ damage-group))
+                           0)
+                       (if (not (char-equal damaged (aref row row-idx)))
+                           (options (1+ row-idx) damage-group)
+                           0)))))))
+      (options 0 0))))
+
+(solve-row "???.### 1,1,3")
+
+(fiveam:test partial
+  (loop for line in (cl-ppcre:split "\\n" eg-input)
+        for solution in '(1 4 1 1 4 10) do
+          (fiveam:is (= solution (solve-row line)))) )
+
+(fiveam:test solutions
+  (fiveam:is (= 7090
+                (reduce #'+
+                        (uiop:read-file-lines "input")
+                        :key #'solve-row))))
-- 
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