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Diffstat (limited to 'year2021/day12/part2.clj')
| -rw-r--r-- | year2021/day12/part2.clj | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/year2021/day12/part2.clj b/year2021/day12/part2.clj new file mode 100644 index 0000000..06b2bcd --- /dev/null +++ b/year2021/day12/part2.clj @@ -0,0 +1,50 @@ +(require '[clojure.string :as str]) +(require '[clojure.core.reducers :as r]) + +; Build list of cave connections: +(def caves (->> (slurp "./in") + (str/split-lines) + (map #(str/split % #"-")) + (map (partial map str)) + (#(concat % (map reverse %))) + )) + +; Try to help execution speed by memoizing cave searches: +(def search-caves + (memoize (fn [id] + (filter + #(and (= (first %) id) + (not (str/starts-with? (second %) "start"))) + caves + )))) + +; Given current path 'path', return a list of valid paths that branch +; from 'path'. Note, paths are stored in reverse order. +(defn get-caves-forward [path] + (r/map #(cons (second %) path) + (r/filter + (fn [cv] + (or + ; Always allow uppercase paths + (< (int (first (second cv))) 96) + ; Or, allow lowercase paths that have never been visited + (not-any? #(= % (second cv)) path) + ; Or, allow one duplicate if there are none yet + (apply distinct? (filter #(= (str/lower-case %) %) path)))) + ; Only work with paths that we connect to + (search-caves (first path)) + ))) + +(loop [paths (into [] (get-caves-forward ["start"])) complete-paths 0] + (let [results (->> paths + (r/mapcat get-caves-forward) + (r/foldcat) + (r/reduce + (fn [r b] (if (not= (first b) "end") + (update r :next-paths #(conj % b)) + (update r :complete-counts inc))) + {:next-paths [] :complete-counts complete-paths}))] + (println (results :complete-counts)) + (when-not (empty? (results :next-paths)) + (recur (results :next-paths) (results :complete-counts))))) + |