AdventOfCode 2022 Day 3

Day3.scala

object Day3 extends Day :
  def toPrio(c:Char):Int = c match {
    case c if c > 'Z' => c - '`'
    case c => c - '@' + 26
  }
  def part1(input:Iterator[String]) = input
    .map(r => r.splitAt(r.length/2))
    .map { case (f, s) => f.toSet.intersect(s.toSet).head }
    .map(toPrio)
    .sum

  def part2(input:Iterator[String]) = input
    .sliding(3,3)
    .map(_.foldLeft(Set.empty[Char]) {
        case (common, sack) if common.isEmpty => sack.toSet
        case (common, sack) => common.intersect(sack.toSet)
      }.head
    )
    .map(toPrio)
    .sum