Day 5

src/day05.scala

@@ -0,0 +1,43 @@
+package aoc
+package day05
+
+val dayNumber = "05"
+
+@main def part1: Unit =
+  println(part1(loadInput(dayNumber)))
+
+@main def part2: Unit =
+  println(part2(loadInput(dayNumber)))
+
+def part1(input: String): String =
+  val Array(rangesInput, ingredientsInput) = input.split("\n\n")
+  val ranges                               =
+    rangesInput.split('\n').map { case s"$from-$to" => (from = from.toLong, to = to.toLong) }
+  ingredientsInput
+    .split('\n').map(_.toLong)
+    .count(i => ranges.exists(r => i >= r.from && i <= r.to)).toString
+
+def part2(input: String): String =
+
+  case class Range(from: Long, to: Long):
+    def contains(i: Long): Boolean      = i >= from && i <= to
+    def contains(other: Range): Boolean = contains(other.from) && contains(other.to)
+    def size                            = Math.max(0, (to - from) + 1)
+    def diff(other: Range): List[Range] =
+      if contains(other) then List(Range(from, other.from - 1), Range(other.to + 1, to))
+      else if other.contains(this) then List()
+      else if contains(other.from) then List(Range(from, other.from - 1))
+      else if contains(other.to) then List(Range(other.to + 1, to))
+      else List(this)
+
+  case class MultiRange(ranges: List[Range] = List.empty):
+    def size                          = ranges.map(_.size).sum
+    def add(range: Range): MultiRange =
+      val remainingRanges = ranges.foldLeft(List(range))((acc, r) => acc.flatMap(_.diff(r)))
+      MultiRange(remainingRanges ++ ranges)
+
+  input
+    .split("\n\n").head
+    .split('\n')
+    .map { case s"$from-$to" => Range(from.toLong, to.toLong) }
+    .foldLeft(MultiRange())(_.add(_)).size.toString