init day 5

2024/src/day05.clj

@@ -0,0 +1,60 @@
+(ns day05
+  (:require [input-manager :refer [get-input]]
+            [core :as c]
+            [clojure.string :as str]))
+
+(let [[a b] (->> (get-input 5)
+                 (partition-by empty?)
+                 (take-nth 2))]
+  (def orderings (->> (map #(str/split % #"\|") a)
+                      (map #(mapv parse-long %))
+                      (group-by first)
+                      (map #(update % 1 (comp set (partial map second))))
+                      (into {})))
+  (def pages (->> (map #(str/split % #",") b)
+                  (map #(mapv parse-long %)))))
+
+(defn get-middle [v]
+  (get v (int (/ (count v) 2))))
+
+(defn ordered? [coll]
+  (reduce (fn [acc p]
+            (if p
+              (if (some acc (orderings p))
+                (reduced false)
+                (conj acc p))
+              (reduced true)))
+          #{}
+          coll))
+
+(defn order [coll]
+  (reduce (fn [acc p]
+            (if p
+              (if-let [idxs (->> (orderings p)
+                                 (filter #(contains? (set acc) %))
+                                 (map #(.indexOf acc %))
+                                 (filter #(not= % -1))
+                                 not-empty)]
+                (let [m (apply min idxs)]
+                  (into [] (concat (take m acc)
+                                   (list p)
+                                   (drop m acc))))
+                (conj acc p))
+              (reduced acc)))
+          []
+          coll))
+
+;; part 1
+(->> pages
+     (filter ordered?)
+     (map get-middle)
+     (reduce +))
+
+;; part 2
+(->> pages
+     (filter #(not (ordered? %)))
+     (map order)
+     (map get-middle)
+     (reduce +))
+
+