Osmos.scala

object Osmos extends App {

  def minOps(armin: Int, motes: Seq[Int]): Int = {

    @annotation.tailrec
    def minOps0(armin: Int, motes: List[Int], limit: Int, count: Int = 0): Int =

      if (motes.isEmpty) count
      else if (count >= limit) limit
      else {
        val (nextArmin, nextMotes, nextLimit, nextCount) =
          if (armin > motes.head)
            (armin + motes.head, motes.tail, limit, count)
          else
            (armin + armin - 1, motes, math.min(limit, count + motes.size), count + 1)
        minOps0(nextArmin, nextMotes, nextLimit, nextCount)
      }

    minOps0(armin, motes.sorted.toList, motes.size)
  }

  def process(lineIn: Iterator[String])(lineOut: String => Unit) = {

    def nextInts() = lineIn.next() split ' ' map (_.toInt)

    for (i <- 1 to lineIn.next().toInt) {

      val Array(a, n) = nextInts()
      val motes = nextInts()

      lineOut(s"Case #$i: ${minOps(a, motes)}")
    }
  }

  val writer = new java.io.PrintWriter("a.large.out")
  try {
    process(io.Source.fromFile("A-large-practice.in").getLines)(writer.println)
  } finally {
    writer.flush(); writer.close()
  }

}