Euler18.scala

object Euler18 extends App {

  val s =
    """|75
       |95 64
       |17 47 82
       |18 35 87 10
       |20 04 82 47 65
       |19 01 23 75 03 34
       |88 02 77 73 07 63 67
       |99 65 04 28 06 16 70 92
       |41 41 26 56 83 40 80 70 33
       |41 48 72 33 47 32 37 16 94 29
       |53 71 44 65 25 43 91 52 97 51 14
       |70 11 33 28 77 73 17 78 39 68 17 57
       |91 71 52 38 17 14 91 43 58 50 27 29 48
       |63 66 04 68 89 53 67 30 73 16 69 87 40 31
       |04 62 98 27 23 09 70 98 73 93 38 53 60 04 23""".stripMargin

  type Row = Vector[Int]
  type Triangle = Vector[Row]

  val t: Triangle = for {r <- s.split("\\n").toVector} yield
                      for {c <- r.split(" ").toVector} yield c.toInt

  def merge(t: Row, b: Row): Row =
    for {i <- t.indices.toVector} yield t(i) + Math.max(b(i), b(i+1))

  val r = t.reduceRight(merge)(0)

  assert(r == 1074)
  println(r)

}