Day 7 p1

2025.clj

@@ -348,3 +348,61 @@ L82")
   (day6-p2 day6-input-test) ;; => 3263827
   (day6-p2 (get-input 6))   ;; => 11136895955912
   :-)
+
+;;  _____                ______ 
+;; |  __ \              |____  |
+;; | |  | | __ _ _   _      / / 
+;; | |  | |/ _` | | | |    / /  
+;; | |__| | (_| | |_| |   / /   
+;; |_____/ \__,_|\__, |  /_/    
+;;                __/ |         
+;;               |___/          
+
+
+
+(def day7-input-test
+  ".......S.......
+...............
+.......^.......
+...............
+......^.^......
+...............
+.....^.^.^.....
+...............
+....^.^...^....
+...............
+...^.^...^.^...
+...............
+..^...^.....^..
+...............
+.^.^.^.^.^...^.
+...............")
+
+(defn day7-p1 [input]
+  (let [lanes (->> (str/split-lines input)
+                    (mapv vec)
+                    (apply mapv vector))
+        length (count (first lanes))]
+    (loop [active-lanes (set (keep-indexed #(when (= (first %2) \S) %1) lanes))
+           idx 2 ;; The splitters start on row 3
+           count 0]
+      (if (= idx length)
+        count
+        (let [[new-lanes added-count]
+              (reduce (fn [[ls c] lane]
+                        (if (not= \^ (get-in lanes [lane idx]))
+                          [ls c]
+                          [(conj (disj ls lane) (dec lane) (inc lane)) (inc c)]))
+                      [active-lanes 0]
+                      active-lanes)]
+         (recur new-lanes (inc idx) (+ count added-count)))))))
+
+(defn day7-p2 [input]
+  ())
+
+(comment
+  (day7-p1 day7-input-test)
+  (day7-p1 (get-input 7))
+  (day7-p2 day7-input-test)
+  (day7-p2 (get-input 7))
+  :-)