138 lines
5.4 KiB
Clojure
138 lines
5.4 KiB
Clojure
(ns advent.pathfind
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(:require [play-clj.core :refer :all])
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(:import (java.lang Math)))
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(def scale 2)
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(def cost-comparator (fn [[a] [b]]
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(let [a (long a)
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b (long b)]
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(unchecked-subtract a b))))
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(defn from-scale [[x y]]
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[(* scale x) (* scale y)])
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(defn to-scale [[x y]]
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[(quot x scale) (quot y scale)])
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(defn printmap [my-map & [skip]]
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(let [skip (or skip 1)]
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(doseq [row (take-nth skip my-map)]
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(println (take-nth skip (map {1 \space 0 "W" "X" "X" "." "."} row))))))
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(defn random-map []
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(-> (vec (take 640 (repeatedly (fn [] (vec (take 480 (repeatedly (fn [] (rand-nth [1 1 1 1 1 0])))))))))
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(update-in [1 1] (constantly 1))
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(update-in [639 479] (constantly 1))))
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(defn neighbors [^long x ^long y my-map]
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(let [left-x (unchecked-subtract x 1)
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right-x (unchecked-add x 1)
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top-y (unchecked-subtract y 1)
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below-y (unchecked-add y 1)
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candidates [[left-x top-y] [x top-y] [right-x top-y]
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[left-x y] [right-x y]
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[left-x below-y] [x below-y] [right-x below-y]]
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height (count (first my-map))
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width (count my-map)]
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(remove (fn [[x y]]
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(= 0 (nth (nth my-map x) y)))
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(filter (fn [[x y]]
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(let [x (long x)
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y (long y)]
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(and (< -1 x width)
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(< -1 y height))))
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candidates))))
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(defn resolve-path [came-from play-loc target-loc]
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(let [came-from (into {} came-from)]
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(if (nil? (came-from target-loc))
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nil
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(loop [path []
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current-node target-loc]
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(if (or (= current-node play-loc)
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(nil? current-node))
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(reverse (conj path (from-scale current-node)))
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(recur
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(conj path (from-scale current-node))
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(came-from current-node)))))))
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(def d2 (- (Math/sqrt 2) 2))
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(defn heuristic ^long [^long goal-x ^long goal-y ^long current-x ^long current-y]
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(let [dist-x (if (< goal-x current-x)
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(unchecked-subtract current-x goal-x)
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(unchecked-subtract goal-x current-x ))
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dist-y (if (< goal-y current-y)
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(unchecked-subtract current-y goal-y)
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(unchecked-subtract goal-y current-y))
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min-dist (double (min dist-x dist-y))]
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(unchecked-add (unchecked-add dist-x dist-y)
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(long (unchecked-multiply (double d2) min-dist)))))
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(defn visit-all [my-map play-loc target-loc]
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(let [play-loc (to-scale play-loc)
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[tx ty :as target-loc] (to-scale target-loc)
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tx (long tx)
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ty (long ty)]
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(if (= 0 (nth (nth my-map tx) ty))
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nil
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(let [^java.util.HashMap cost-so-far (java.util.HashMap.)
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_ (.put cost-so-far play-loc 0)
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^java.util.HashMap came-from (java.util.HashMap.)
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^java.util.PriorityQueue fronteir (java.util.PriorityQueue. (/ (* 320 240) scale) cost-comparator)]
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(.offer fronteir [0 play-loc])
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(loop [current-loc (.poll fronteir)]
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(if (or (nil? current-loc)
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(= (nth current-loc 1) target-loc))
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(resolve-path came-from play-loc target-loc)
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(let [[_ [cx cy :as current-loc]] current-loc
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cx (long cx)
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cy (long cy)]
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(doseq [[nx ny :as neighbor] (neighbors cx cy my-map)
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:let [nx (long nx)
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ny (long ny)]]
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(let [cost-for-neighbor (.get cost-so-far neighbor)
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new-cost (unchecked-add (long (.get cost-so-far current-loc))
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(long (nth (nth my-map nx) ny)))]
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(when (or (nil? cost-for-neighbor)
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(< new-cost cost-for-neighbor))
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(.put came-from neighbor current-loc)
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(.put cost-so-far neighbor new-cost)
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(.offer fronteir [(unchecked-add new-cost (heuristic tx ty nx ny))
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neighbor]))))
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(recur (.poll fronteir)))))))))
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(defn print-resolved [path my-map]
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(doseq [row (reduce (fn [acc path]
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(if path
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(update-in acc (reverse path) (constantly "X"))
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acc))
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my-map
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path)]
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(println (map {1 \space 5 "." 0 "W" "X" "X"} row)))
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nil)
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(defn test-pathfind []
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(let [my-map (random-map)
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path (visit-all my-map [1 1] [639 479 ])]
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(print-resolved path my-map)
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(println path)))
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(defn map-from-resource [filename]
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(let [pm (pixmap filename)
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black (color 0 0 0 255)
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painful (color 255 0 0 255)
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result (transient [])
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scale (long scale)
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height (long (pixmap! pm :get-height))]
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(doseq [^long x (range (/ (pixmap! pm :get-width) scale))
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^long y (range (/ height scale))
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:let [
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current-color (color (pixmap! pm :get-pixel (unchecked-multiply scale x) (unchecked-subtract height (unchecked-multiply scale y))))]]
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(conj! result (cond
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(color! current-color :equals black) 0
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(color! current-color :equals painful) 2
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:else 1)))
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(partition (/ (pixmap! pm :get-height) scale) (persistent! result) )))
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