Add 2023 day 9

2023/day9.clj

@@ -0,0 +1,26 @@
+(ns clojure-aoc.core (:gen-class)
+  (:require clojure.string))
+
+(def input (-> (slurp "input.txt") (clojure.string/split #"\n")))
+
+(defn extrapolate [coll back?]
+  (if (every? #(= % 0) coll)
+    0
+    (let [differences (map - (next coll) coll)
+          ex-next (extrapolate differences back?)]
+      (if back?
+        (-> (first coll) (- ex-next))
+        (-> (last coll) (+ ex-next))))))
+
+(defn oasis-report [back?]
+  (->> input
+    (map (fn [line] (map #(Integer/parseInt %) (clojure.string/split line #" "))))
+    (map #(extrapolate % back?))
+    (apply +)))
+
+(def part1 (oasis-report false))
+
+(def part2 (oasis-report true))
+
+(defn -main [& args]
+  (str part1 " " part2))