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Day20.scala
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Day20.scala
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package AdventOfCode2016
object Day20:
case class Range(start: Long, end: Long):
def size = end - start + 1
def subtract(other: Range): Seq[Range] =
val (s1, e1) = (start, end)
val (s2, e2) = (other.start, other.end)
if s2 <= s1 && e1 <= e2 then Seq()
else if s1 < s2 && e2 < e1 then Seq(Range(s1, s2 - 1), Range(e2 + 1, e1))
else if s1 <= e2 && e2 < e1 then Seq(Range(e2 + 1, e1))
else if s1 < s2 && s2 <= e1 then Seq(Range(s1, s2 - 1))
else Seq(this)
def parse(input: Seq[String]): Seq[Range] = input.map { line =>
val Array(start, end) = line.split("-").map(_.toLong)
Range(start, end)
}
def intersect(input: Seq[String], max: Long): Seq[Range] =
val initial = Seq(Range(0, max))
parse(input).foldLeft(initial)((remaining, next) => remaining.flatMap(_.subtract(next)))
def part1(input: Seq[String], max: Long): Long = intersect(input, max).map(_.start).min
def part2(input: Seq[String], max: Long): Long = intersect(input, max).map(_.size).sum
def main(args: Array[String]): Unit =
val data = io.Source.fromResource("AdventOfCode2016/Day20.txt").getLines().toSeq
val max = 4294967295L
println(part1(data, max))
println(part2(data, max))