do day 3

2017/src/day03.clj

@@ -0,0 +1,51 @@
+(ns day03
+  (:require input-manager))
+
+(def input (parse-long (input-manager/get-input-raw 2017 3)))
+
+(def directions [:right :up :left :down])
+(def to-the-left {:right :up
+                  :up :left
+                  :down :right
+                  :left :down})
+(def cardinal-dir-offsets {:right [1 0]
+                           :left [-1 0]
+                           :down [0 -1]
+                           :up [0 1]})
+
+(def all-offsets #{[1 0] [-1 0] [0 -1] [0 1] [1 1] [-1 -1] [1 -1] [-1 1]})
+
+(->> (loop [loc [1 0]
+            i 2
+            grid {[0 0] 1}
+            [dir :as dirs] (cycle directions)]
+       (if (< i input)
+         (let [left-loc (mapv + loc (cardinal-dir-offsets (to-the-left dir)))
+               grid' (assoc grid loc i)
+               i' (inc i)]
+           (if (contains? grid left-loc)
+             (recur (mapv + loc (cardinal-dir-offsets dir)) i' grid' dirs)
+             (recur left-loc i' grid' (rest dirs))))
+         loc))
+     (map abs)
+     (apply +))
+
+(->> (loop [loc [1 0]
+            grid {[0 0] 1}
+            [dir :as dirs] (cycle directions)]
+       (let [left-loc (mapv + loc (cardinal-dir-offsets (to-the-left dir)))
+             value (->> all-offsets
+                        (map (comp
+                              #(or (grid %) 0)
+                              #(mapv + % loc)))
+                        (reduce +))
+             grid' (assoc grid loc value)]
+         (cond
+           (> value input)
+           value
+
+           (contains? grid left-loc)
+           (recur (mapv + loc (cardinal-dir-offsets dir)) grid' dirs)
+
+           :else
+           (recur left-loc grid' (rest dirs))))))

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 +))