Adding day 1

day1/part2.scala

@@ -0,0 +1,23 @@
+/**
+ * Usage: scala part2.scala < input
+ */
+
+import scala.io.StdIn
+import scala.collection.Iterator
+
+val items = Stream
+  .continually(StdIn.readLine)
+  .takeWhile(_ != null)
+  .map(Integer.parseInt)
+  .toList
+
+println(
+Stream
+  .continually(items.toStream)
+  .flatten
+  .scanLeft(0)(_ + _)
+  .scanLeft(Map.empty[Int, Int]){case (acc, item) => acc + (item -> (acc.getOrElse(item, 0) + 1)) }
+  .filter(_.count(_._2 == 2) > 0)
+  .map(_.maxBy(_._2))
+  .head
+)