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159 lines
6.4 KiB
Clojure
159 lines
6.4 KiB
Clojure
3 years ago
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(require '[clojure.core.reducers :as r])
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(require 'clojure.string)
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(defn build-scanner-reports
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"Splits slurped, split-lines'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
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(->> (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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(let [or-vec [[[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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chosen (get or-vec or-index)]
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(map #(orient (map - %) chosen) 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 [[[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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(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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(let [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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(filter some?
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(map
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(fn [[orientation link]]
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(let [distinct-points (into [] (distinct (reduce concat link)))
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link-results
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(into '()
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(r/fold (quot (count distinct-points) 16) r/cat
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(fn [pcoll point]
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(if-not (empty? pcoll)
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pcoll
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(let [occurrance-count (reduce
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#(cond-> %1
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(not (empty? (filter (partial = point) %2)))
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inc)
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1 link)]
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(cond-> pcoll (> occurrance-count 11) (r/append! point)))))
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distinct-points))]
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(when (not (empty? link-results))
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[orientation (first link-results)])))
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(into [] 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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(let [s2-ored (scanner-orientation s2 s2-or)]
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(distinct (concat s1 (map #(point-add s2-coord (map - %)) s2-ored)))))
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(def reports (->> (slurp "./in")
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(clojure.string/split-lines)
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(build-scanner-reports)
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(vec)))
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(let [[beacon-count scanner-coords]
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(loop [new-reps reports sc-coords '([0 0 0]) i (range 1 (count reports))]
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(println "Trying" (first i) (map count new-reps))
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(if (nil? (first i))
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; reached end (uh oh?)
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[(count new-reps) sc-coords]
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; scan for links to report i
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(let [found (scanner-find-connection (first new-reps)
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(get new-reps (first i)))]
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(if (empty? found)
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; no match, move to next i
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(recur new-reps sc-coords (rest i))
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(do (println " Found" found)
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(recur
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(-> new-reps
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; replace index zero with merged report
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(assoc 0 (scanner-merge (first new-reps)
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(get new-reps (first i))
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(first (first found))
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(second (first found))))
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; remove report we pulled from
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(#(concat (subvec % 0 (first i))
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(subvec % (inc (first i)))))
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; back to vector
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(vec))
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(conj sc-coords (second (first found)))
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; begin new scan
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(range 1 (count new-reps))))))))]
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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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