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45 lines
1.6 KiB
Clojure

(def target-area [[169 -68] [206 -108]])
;(def target-area [[20 -5] [30 -10]])
(def initial-pos [0 0])
(defn beyond-target? [[[tbx tby] [tex tey]] [x y]]
(or (> x tex) (< y tey)))
(defn within-target? [[[tbx tby] [tex tey]] [x y]]
(and (>= x tbx) (<= x tex) (<= y tby) (>= y tey)))
(defn apply-velocity [[[px py] [vx vy]]]
[[(+ px vx) (+ py vy)] [(if (pos? vx) (dec vx) 0) (dec vy)]])
(defn path-builder [vel] (iterate apply-velocity [initial-pos vel]))
(defn build-path [target vel]
(->> (path-builder vel)
(take-while (comp not (partial beyond-target? target) first))
(map first)))
(defn path-height [target vel]
(let [path (build-path target vel)]
(when (within-target? target (last path))
(apply max (map second path)))))
; Used to determine best x velocity for highest path
(def tnum-seq (iterate #(do [(apply + %) (inc (second %))]) [0 1]))
(let [[tb te] target-area
lowest-x (second (last (take-while #(< (first %) (first tb)) tnum-seq)))
lowest-y (second te)
valid-paths (filter (comp some? first)
(for [y (range lowest-y 2000)]
[(path-height target-area [lowest-x y]) y]))
highest-path (reduce #(if (> (first %1) (first %2)) %1 %2) valid-paths)]
(println (first highest-path))
(println
(count
(filter (partial within-target? target-area)
(let [ys [(second te) (second highest-path)]]
(for [x (range lowest-x (inc (first te)))
y (range (apply min ys) (inc (apply max ys)))]
(last (build-path target-area [x y]))))))))