Day 6

2025.clj

@@ -12,6 +12,7 @@
 
 (def directions {:N  [-1  0] :S   [1 0] :W  [0 -1] :E  [0 1]
                  :NW [-1 -1] :NE [-1 1] :SW [1 -1] :SE [1 1]})
+
 ;;  _____                __ 
 ;; |  __ \              /_ |
 ;; | |  | | __ _ _   _   | |
@@ -288,3 +289,62 @@ L82")
   (day5-p2 day5-input-test)
   (day5-p2 (get-input 5))
   :-)
+
+;;  _____                  __  
+;; |  __ \                / /  
+;; | |  | | __ _ _   _   / /_  
+;; | |  | |/ _` | | | | | '_ \ 
+;; | |__| | (_| | |_| | | (_) |
+;; |_____/ \__,_|\__, |  \___/ 
+;;                __/ |        
+;;               |___/         
+
+(def day6-input-test
+"123 328  51 64 
+ 45 64  387 23 
+  6 98  215 314
+*   +   *   +  ")
+
+(defn day6-p1 [input]
+  (let [parsed (->> (str/split-lines input)
+                    (mapv #(->> (str/split % #"\s+")
+                                (remove empty?))))]
+    (->> (butlast parsed)
+         (mapv #(mapv parse-long %))
+         (into [(mapv #(resolve (symbol %)) (last parsed))])
+         (apply mapv vector)
+         (map #(apply (first %) (rest %)))
+         (reduce +))))
+
+(defn day6-p2 [input]
+  (let [grid (->> (str/split-lines input)
+                  (mapv vec))
+        row-count (count grid)]
+    (loop [curr-col (dec (count (first grid)))
+           curr-row 0
+           curr-num-str ""
+           nums []
+           total 0]
+      (if (= curr-col -1)
+        total
+        (let [curr (get-in grid [curr-row curr-col])
+              last-row (= curr-row (dec row-count))]
+          (cond
+            (Character/isDigit curr)
+            (recur curr-col (mod (inc curr-row) row-count) (str curr-num-str curr) nums total)
+
+            last-row
+            (let [sum (parse-long curr-num-str)]
+              (if (#{\+ \*} curr)
+                (recur (dec curr-col) 0 "" [] (+ total (reduce (resolve (symbol (str curr))) (conj nums sum))))
+                (recur (dec curr-col) 0 "" (if sum (conj nums sum) []) total)))
+
+            :else
+            (recur curr-col (mod (inc curr-row) row-count) curr-num-str nums total)))))))
+
+(comment
+  (day6-p1 day6-input-test) ;; => 4277556
+  (day6-p1 (get-input 6))   ;; => 6343365546996
+  (day6-p2 day6-input-test) ;; => 3263827
+  (day6-p2 (get-input 6))   ;; => 11136895955912
+  :-)