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51 lines
1.8 KiB
Clojure
51 lines
1.8 KiB
Clojure
(require '[clojure.string :as str])
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(require '[clojure.core.reducers :as r])
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; Build list of cave connections:
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(def caves (->> (slurp "./in")
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(str/split-lines)
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(map #(str/split % #"-"))
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(map (partial map str))
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(#(concat % (map reverse %)))
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))
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; Try to help execution speed by memoizing cave searches:
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(def search-caves
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(memoize (fn [id]
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(filter
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#(and (= (first %) id)
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(not (str/starts-with? (second %) "start")))
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caves
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))))
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; Given current path 'path', return a list of valid paths that branch
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; from 'path'. Note, paths are stored in reverse order.
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(defn get-caves-forward [path]
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(r/map #(cons (second %) path)
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(r/filter
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(fn [cv]
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(or
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; Always allow uppercase paths
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(< (int (first (second cv))) 96)
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; Or, allow lowercase paths that have never been visited
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(not-any? #(= % (second cv)) path)
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; Or, allow one duplicate if there are none yet
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(apply distinct? (filter #(= (str/lower-case %) %) path))))
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; Only work with paths that we connect to
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(search-caves (first path))
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)))
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(loop [paths (into [] (get-caves-forward ["start"])) complete-paths 0]
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(let [results (->> paths
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(r/mapcat get-caves-forward)
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(r/foldcat)
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(r/reduce
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(fn [r b] (if (not= (first b) "end")
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(update r :next-paths #(conj % b))
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(update r :complete-counts inc)))
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{:next-paths [] :complete-counts complete-paths}))]
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(println (results :complete-counts))
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(when-not (empty? (results :next-paths))
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(recur (results :next-paths) (results :complete-counts)))))
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