Day 2

src/day02.scala

@@ -0,0 +1,46 @@
+package aoc
+package day02
+
+import scala.annotation.tailrec
+
+val dayNumber = "02"
+
+@main def part1: Unit =
+  println(part1(loadInput(dayNumber)))
+
+@main def part2: Unit =
+  println(part2(loadInput(dayNumber)))
+
+def part1(input: String): String =
+
+  def isValid(id: String): Boolean =
+    if id.length % 2 == 0 then
+      val (left, right) = id.splitAt(id.length / 2)
+      left != right
+    else true
+
+  input
+    .split(",")
+    .map { case s"$from-$to" => from.toLong to to.toLong }
+    .map(_.filterNot(id => isValid(id.toString)).sum)
+    .sum
+    .toString
+
+def part2(input: String): String =
+
+  def isValid(id: Long): Boolean =
+    @tailrec
+    def rec(id: String, groupsCount: Int): Boolean =
+      if groupsCount < 1 then true
+      else if id.length % groupsCount == 0 then
+        id.grouped(groupsCount).distinct.length > 1 && rec(id, groupsCount - 1)
+      else rec(id, groupsCount - 1)
+
+    rec(id.toString, id.toString.length - 1)
+
+  input
+    .split(",")
+    .map { case s"$from-$to" => from.toLong to to.toLong }
+    .map(_.filterNot(isValid).sum)
+    .sum
+    .toString