mirror of
https://github.com/Ajetski/advent-of-code.git
synced 2025-09-30 11:33:19 -09:00
126 lines
3.9 KiB
Clojure
126 lines
3.9 KiB
Clojure
(ns day10
|
|
(:require
|
|
[clojure.math :as math]
|
|
[core :refer [get-puzzle-input]]))
|
|
|
|
(def input (get-puzzle-input 10))
|
|
|
|
(def pipe-out-types {:left #{\- \7 \J \S}
|
|
:right #{\- \F \L \S}
|
|
:up #{\| \L \J \S}
|
|
:down #{\| \7 \F \S}})
|
|
|
|
(def char-map
|
|
(->> input
|
|
(map-indexed (fn [row line]
|
|
(map-indexed (fn [col c]
|
|
[[row col] c])
|
|
line)))
|
|
(apply concat)
|
|
(into {})))
|
|
|
|
(def opposite-dir {:left :right
|
|
:right :left
|
|
:up :down
|
|
:down :up})
|
|
|
|
(def start (->> char-map
|
|
(filter #(= \S (second %)))
|
|
ffirst))
|
|
|
|
(defn follow-dir [loc dir]
|
|
(condp = dir
|
|
:up (update loc 0 dec)
|
|
:down (update loc 0 inc)
|
|
:left (update loc 1 dec)
|
|
:right (update loc 1 inc)))
|
|
|
|
(def char-dir-map {\| [:up :down]
|
|
\- [:left :right]
|
|
\L [:right :up]
|
|
\F [:right :down]
|
|
\J [:left :up]
|
|
\7 [:left :down]})
|
|
|
|
(defn follow-pipe [loc from]
|
|
(let [c (char-map loc)]
|
|
(if (and (not (nil? c))
|
|
(not= \. c))
|
|
(let [dir (->> c
|
|
(char-dir-map)
|
|
(filter #(not= from %))
|
|
(first))
|
|
new-loc (follow-dir loc dir)]
|
|
(if ((pipe-out-types (opposite-dir dir)) (char-map new-loc))
|
|
[new-loc dir]
|
|
nil))
|
|
nil)))
|
|
|
|
;; part 1
|
|
(->> (for [start-dir [:up :down :left :right]]
|
|
(loop [loc (follow-dir start start-dir)
|
|
cnt 0
|
|
from (opposite-dir start-dir)
|
|
visited #{}]
|
|
(if (or (= loc nil) (= loc start))
|
|
cnt
|
|
(let [res (follow-pipe loc from)]
|
|
(if (or (= res nil)
|
|
(visited (first res)))
|
|
nil
|
|
(recur (first res)
|
|
(inc cnt)
|
|
(opposite-dir (second res))
|
|
(conj visited loc)))))))
|
|
(filter (comp not nil?))
|
|
(map #(/ % 2))
|
|
(map math/round)
|
|
(into #{})
|
|
(apply max))
|
|
|
|
;; part 2
|
|
(let [path (->> (for [start-dir [:right :left :up :down]]
|
|
(loop [loc (follow-dir start start-dir)
|
|
route []
|
|
from (opposite-dir start-dir)
|
|
visited #{}]
|
|
(if (or (= loc nil) (= loc start))
|
|
route
|
|
(let [res (follow-pipe loc from)]
|
|
(if (or (= res nil)
|
|
(visited (first res)))
|
|
nil
|
|
(recur (first res)
|
|
(conj route loc)
|
|
(opposite-dir (second res))
|
|
(conj visited loc)))))))
|
|
(filter (comp not nil?))
|
|
(sort-by #(/ (count %) 2) >)
|
|
first
|
|
(into #{})
|
|
(#(conj % start)))
|
|
by-row (->> path
|
|
(group-by first)
|
|
(map #(update % 1 (partial map second)))
|
|
(map #(update % 1 sort))
|
|
(into {}))
|
|
by-col (->> path
|
|
(group-by second)
|
|
(map #(update % 1 (partial map first)))
|
|
(map #(update % 1 sort))
|
|
(into {}))
|
|
coords (->> char-map
|
|
(map first)
|
|
(filter (comp not path)))]
|
|
(->> coords
|
|
(filter (fn [[row col]]
|
|
(or (->> row
|
|
by-row
|
|
(partition 2)
|
|
(some #(< (first %) col (second %))))
|
|
(->> col
|
|
by-col
|
|
(partition 2)
|
|
(some #(< (first %) row (second %)))))))
|
|
count))
|