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45 lines
1.4 KiB
Clojure
45 lines
1.4 KiB
Clojure
(require '[clojure.core.reducers :as r])
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(def input (->> (slurp "./in")
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(clojure.string/split-lines)
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(mapv (partial mapv (comp read-string str)))
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(#(for [y (range 0 (count %)) x (range 0 (count (first %)))]
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{[y x] (get-in % [y x])}))
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(into {})))
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(defn min-distance [dist Q]
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(r/fold
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(r/monoid
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#(if (< (first %1) (first %2)) %1 %2)
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(constantly [##Inf []]))
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(r/monoid
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#(if (< (first %1) (dist %2)) %1 [(dist %2) %2])
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(constantly [##Inf []]))
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(r/filter
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(partial contains? dist)
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(apply vector Q))))
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(defn find-neighbors [Q u]
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(filter #(contains? Q %) [(update u 0 inc)
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(update u 0 dec)
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(update u 1 inc)
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(update u 1 dec)]))
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(let [dim (apply max (map first (keys input)))]
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(loop [Q (apply sorted-set (keys input))
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dist (assoc (hash-map) [0 0] 0)]
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(when (= 0 (rem (count Q) 500)) (println (count Q)))
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(if (empty? Q)
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(println (dist [dim dim]))
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(let [[u vu] (min-distance dist Q)]
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(recur
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(disj Q vu)
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(reduce
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#(let [alt (+ u (input %2))]
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(cond-> %1
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(or (not (contains? dist %2)) (< alt (dist %2)))
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(assoc %2 alt)))
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dist
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(find-neighbors Q vu)))))))
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