1 files changed, 37 insertions, 0 deletions
diff --git a/day17/partboth.clj b/day17/partboth.clj
new file mode 100644
index 0000000..91b005c
--- /dev/null
+++ b/day17/partboth.clj
@@ -0,0 +1,37 @@
+(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)] [(cond-> vx (pos? vx) dec) (dec vy)]])
+
+(defn build-path [target vel]
+  (->> (iterate apply-velocity [initial-pos vel])
+       (take-while (comp not (partial beyond-target? target) first))
+       (mapv 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)))
+      highest-y    (dec (Math/abs (second te)))]
+  (println
+    (path-height target-area [lowest-x highest-y])
+    (count
+      (filter (partial within-target? target-area)
+        (for [x (range lowest-x (inc (first te)))
+              y (range (second te) (inc highest-y))]
+          (last (build-path target-area [x y])))))))
+