1 files changed, 34 insertions, 0 deletions
diff --git a/day17/part1.clj b/day17/part1.clj
new file mode 100644
index 0000000..220e408
--- /dev/null
+++ b/day17/part1.clj
@@ -0,0 +1,34 @@
+(def target-area [[169 -8] [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 [[pos vel]]
+  [[(+ (first pos) (first vel)) (+ (second pos) (second vel))]
+   [(cond-> (first vel) (> (first vel) 0) dec (< (first vel) 0) inc) (dec (second vel))]])
+
+(defn path-builder [vel] (iterate apply-velocity [initial-pos vel]))
+
+(defn build-path [target vel]
+  (map first
+    (take-while (comp not (partial beyond-target? target) first)
+                (path-builder vel))))
+
+(defn path-height [target vel]
+  (let [path (build-path target vel)]
+    (when (within-target? target (last path))
+      (apply max (map second path)))))
+
+(def tnum-seq (iterate #(do [(+ (first %) (second %)) (inc (second %))]) [0 1]))
+
+(let [x (second (last (take-while #(< (first %) (first (first target-area))) tnum-seq)))]
+  (println
+    (apply max
+      (filter some?
+        (for [y (range -2000 2000)] (path-height target-area [x y]))))))
+