import scala.io.Source

object OutRunScala {

  def solve(source: Source): Int = {
    source
      .getLines()
      .drop(1)
      .map(_.trim)
      .filterNot(_.isEmpty)
      .map(_.split("\\s+"))
      .map(_.map(_.toInt))
      .foldLeft(IndexedSeq[Int]())(fold)
      .max
  }
  
  private def fold(acc: IndexedSeq[Int], row: Array[Int]): IndexedSeq[Int] = {
    for {
      i <- 0 until row.size
      n <- Some(row(i))
      l <- if (i == acc.size) Some(0) else Some(acc(i))
      r <- if (i == 0) Some(0) else Some(acc(i - 1))
    } yield n + math.max(l, r)
  }
  
  def main(args: Array[String]) {
    val start = System.currentTimeMillis
    val result = solve(Source fromFile args(0))
    val duration = System.currentTimeMillis - start
    println(s"# result: $result")
    println(s"# execution duration: $duration ms")
  }
}