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99 lines
3.7 KiB
Clojure
99 lines
3.7 KiB
Clojure
(require '[clojure.core.reducers :as r])
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(require 'clojure.string)
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(def orientation-vectors
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[[[1 0 0] [0 1 0] [0 0 1]]
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[[1 0 0] [0 0 -1] [0 1 0]]
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[[1 0 0] [0 -1 0] [0 0 -1]]
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[[1 0 0] [0 0 1] [0 -1 0]]
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[[-1 0 0] [0 -1 0] [0 0 1]]
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[[-1 0 0] [0 0 -1] [0 -1 0]]
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[[-1 0 0] [0 1 0] [0 0 -1]]
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[[-1 0 0] [0 0 1] [0 1 0]]
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[[0 0 -1] [1 0 0] [0 -1 0]]
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[[0 1 0] [1 0 0] [0 0 -1]]
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[[0 0 1] [1 0 0] [0 1 0]]
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[[0 -1 0] [1 0 0] [0 0 1]]
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[[0 0 1] [-1 0 0] [0 -1 0]]
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[[0 1 0] [-1 0 0] [0 0 1]]
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[[0 0 -1] [-1 0 0] [0 1 0]]
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[[0 -1 0] [-1 0 0] [0 0 -1]]
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[[0 -1 0] [0 0 -1] [1 0 0]]
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[[0 0 1] [0 -1 0] [1 0 0]]
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[[0 1 0] [0 0 1] [1 0 0]]
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[[0 0 -1] [0 1 0] [1 0 0]]
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[[0 0 1] [0 1 0] [-1 0 0]]
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[[0 -1 0] [0 0 1] [-1 0 0]]
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[[0 0 -1] [0 -1 0] [-1 0 0]]
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[[0 1 0] [0 0 -1] [-1 0 0]]])
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(defn build-scanner-reports
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"Splits slurped, split-line'd input by scanner."
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[input-lines]
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(loop [scanners [] rem-input input-lines]
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(if (empty? rem-input)
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scanners
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(let [[this nxt] (split-with (comp not empty?) rem-input)]
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(recur (->> (rest this)
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(map #(read-string (clojure.string/join ["[" % "]"])))
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(conj scanners))
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(rest nxt))))))
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(defn point-add [[a b c] [d e f]] [(+ a d) (+ b e) (+ c f)])
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(defn orient [[x y z] [[a b c] [d e f] [g h i]]]
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[(+ (* x a) (* y d) (* z g)) (+ (* x b) (* y e) (* z h)) (+ (* x c) (* y f) (* z i))])
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(defn scanner-orientation [report or-index]
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(map #(orient (map - %) (get orientation-vectors or-index)) report))
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(defn scanner-orientations
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"Builds list of scanner reports adjusted for all possible orientations."
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[report]
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(for [or-vec orientation-vectors]
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(map #(orient (map - %) or-vec) report)))
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(defn scanner-build-potential-links
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"Builds a list for each s2 orientation that contains lists of each s1 point
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added to the corresponding s2 point."
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[s1 s2]
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(for [s2-or (scanner-orientations s2)]
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(for [i (range 0 (count s1))]
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(for [j (range 0 (count s2-or))]
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(point-add (nth s1 i) (nth s2-or j))))))
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(defn scanner-find-connection
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"Attempt to determine if s1 and s2 are linked through common beacons."
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[s1 s2]
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(loop [potential-links (as-> (scanner-build-potential-links s1 s2) $
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(for [i (range 0 (count $))] [i (nth $ i)])
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(into [] $))]
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(when-let [[orientation link] (first potential-links)]
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(if-let [match (first (drop-while #(< (val %) 12) (frequencies (reduce concat link))))]
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[orientation (key match)]
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(recur (rest potential-links))))))
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(defn scanner-merge
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"Merges the report of linked scanner s2 into scanner s1."
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[s1 s2 s2-or s2-coord]
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(vec (into (set s1) (map #(point-add s2-coord (map - %)) (scanner-orientation s2 s2-or)))))
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(let [[beacon-count scanner-coords]
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(loop [new-reps (->> (slurp "./in") clojure.string/split-lines build-scanner-reports)
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sc-coords '([0 0 0])
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next-reps (rest new-reps)]
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(if-let [next-rep (first next-reps)]
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(if-let [[found-or found-coord] (scanner-find-connection (first new-reps) next-rep)]
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(let [new-base (scanner-merge (first new-reps) next-rep found-or found-coord)
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newest-reps (->> (assoc new-reps 0 new-base) (filterv (partial not= next-rep)))]
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(println "found" found-coord)
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(recur newest-reps (conj sc-coords found-coord) (rest newest-reps)))
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(recur new-reps sc-coords (rest next-reps)))
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[(count (first new-reps)) sc-coords]))]
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(println "Part 1:" beacon-count)
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(println "Part 2:"
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(apply max
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(for [p1 scanner-coords p2 scanner-coords :when (not= p1 p2)]
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(apply + (map #(Math/abs %) (point-add (map - p1) p2)))))))
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