aoc_day6_fast

aoc_day6_fast.scala

def day6fast(chars: Iterator[Char], targetNum: Int): Option[Int] = {
  val buffer = scala.collection.mutable.ListBuffer.empty[Char]
  try {
    var i = 0
    while (true) {
      val c = chars.next()
      if (buffer.length == targetNum) {
        buffer.dropInPlace(1)
      }
      buffer.append(c)
      if (buffer.distinct.size == targetNum) return Some(i + 1)
      i += 1
    }
    None
  } catch {
    case _ => None
  }
}
day6fast("mjqjpqmgbljsphdztnvjfqwrcgsmlb".iterator, 14)
day6fast("bvwbjplbgvbhsrlpgdmjqwftvncz".iterator, 14)