init day3

2024/src/core.clj

@@ -9,4 +9,11 @@
   (str/split s #"\s+"))
 
 (defn get-match-groups [regex s]
-  (->> s (re-seq regex) first rest))
+  (->> s (re-seq regex) (map rest)))
+
+(defn re-pos [re s]
+        (loop [m (re-matcher re s)
+               res {}]
+          (if (.find m)
+            (recur m (assoc res (.start m) (.group m)))
+            res)))

2024/src/day03.clj

@@ -0,0 +1,39 @@
+(ns day03
+  (:require [core :as c]
+            [input-manager :refer [get-input]]
+            [clojure.string :as str]))
+
+(def input (str/join (get-input 3)))
+
+(defn parse-muls
+  "takes in a string containing mul instructions
+  returns list of parsed integral multiplication results"
+  [s]
+  (->> s
+       (re-seq #"mul\((\d\d?\d?),(\d\d?\d?)\)")
+       (map rest)
+       (map #(map parse-long %))
+       (map #(reduce * %))))
+
+;; part 1
+(->> input
+     parse-muls
+     (reduce +))
+
+;; part 2
+(->> input
+     (c/re-pos #"mul\((\d\d?\d?),(\d\d?\d?)\)|(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)
+