cons is for boomers

2024/src/day03.clj

@@ -1,37 +1,31 @@
 (ns day03
-  (:require [core :as c]
-            [input-manager :refer [get-input]]
+  (:require [input-manager]
             [clojure.string :as str]))
 
-(def input (str/join (get-input 3)))
+(def input (input-manager/get-input-raw 2024 3))
 
-(defn parse-muls
-  "takes in a string containing mul instructions
-  returns list of parsed integral multiplication results"
-  [s]
-  (->> (c/get-match-groups #"mul\((\d{1,3}),(\d{1,3})\)" s)
-       (map #(map parse-long %))
-       (map #(reduce * %))))
+(defn compute-muls [s]
+  (map (comp #(reduce * %)
+             #(map parse-long %)
+             #(str/split % #",")
+             #(subs % 4 (dec (count %)))) ;; remove `mul(` prefix and `)` suffix
+       s))
+
+(defn enforce-toggles [[el & rst]]
+  (cond (= el "do()")    (recur rst)
+        (= el "don't()") (recur (drop-while #(not= % "do()") rst))
+        el               (conj (lazy-seq (enforce-toggles rst)) el)))
 
 ;; part 1
 (->> input
-     parse-muls
+     (re-seq #"mul\(\d{1,3},\d{1,3}\)")
+     compute-muls
      (reduce +))
 
 ;; part 2
 (->> input
-     (c/re-pos #"mul\((\d{1,3}),(\d{1,3})\)|(do\(\))|(don't\(\))")
-     (sort-by key)
-     (reduce
-      (fn [acc [_idx instr]]
-        (cond
-          (.startsWith instr "mul") (if (:on acc)
-                                      (update acc :val
-                                              + (->> instr parse-muls first))
-                                      acc)
-          (.startsWith instr "don't") (assoc acc :on false)
-          (.startsWith instr "do") (assoc acc :on true)))
-      {:on true
-       :val 0})
-     :val)
+     (re-seq #"mul\(\d{1,3},\d{1,3}\)|do\(\)|don't\(\)")
+     enforce-toggles
+     compute-muls
+     (reduce +))