add day 15

1 files changed, 20 insertions, 0 deletions

diff --git a/year2020/day1/part2.clj b/year2020/day1/part2.clj
new file mode 100644
index 0000000..0b6ef9d
--- /dev/null
+++ b/year2020/day1/part2.clj
@@ -0,0 +1,20 @@
+(require 'clojure.set)
+
+(defn find-sum [sum lst]
+  (->> lst
+       ((juxt set (comp set #(map (partial - sum) %))))
+       (apply clojure.set/intersection)
+       (vec)))
+
+(->> (slurp "./in")
+     clojure.string/split-lines
+     ((comp set (partial map read-string)))
+     ((fn [lst]
+       (reduce
+         #(let [fnd (find-sum (- 2020 %2) (clojure.set/difference lst #{%2}))]
+            (if (empty? fnd) %1 [%2 fnd]))
+         []
+         lst)))
+     flatten
+     (apply *)
+     (println))