euler_p11.scala

//70600674
val table = List(
  List(8, 2,22,97,38,15, 0, 40, 0, 75, 4, 5, 7, 78, 52, 12, 50, 77, 91, 8),
  List(49, 49,99,40,17,81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48, 04, 56, 62, 0),
  List(81, 49,31,73,55,79, 14, 29, 93, 71, 40, 67, 53, 88, 30, 03, 49, 13, 36, 65),
  List(52, 70,95,23,04,60, 11, 42, 69, 24, 68, 56, 01, 32, 56, 71, 37, 02, 36, 91),
  List(22, 31,16,71,51,67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80),
  List(24, 47,32,60,99,03, 45, 02, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50),
  List(32, 98,81,28,64,23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70),
  List(67, 26,20,68,02,62, 12, 20, 95, 63, 94, 39, 63, 8, 40, 91, 66, 49, 94, 21),
  List(24, 55,58,05,66,73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72),
  List(21, 36,23,9,75,0, 76, 44, 20, 45, 35, 14, 00, 61, 33, 97, 34, 31, 33, 95),
  List(78, 17,53,28,22,75, 31, 67, 15, 94, 03, 80, 04, 62, 16, 14, 9, 53, 56, 92),
  List(16, 39,05,42,96,35, 31, 47, 55, 58, 88, 24, 00, 17, 54, 24, 36, 29, 85, 57),
  List(86, 56,00,48,35,71, 89, 07, 05, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58),
  List(19, 80,81,68,05,94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77, 04, 89, 55, 40),
  List(04, 52,8,83,97,35, 99, 16, 07, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66),
  List(88, 36,68,87,57,62, 20, 72, 03, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69),
  List(04, 42,16,73,38,25, 39, 11, 24, 94, 72, 18, 8, 46, 29, 32, 40, 62, 76, 36),
  List(20, 69,36,41,72,30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74, 04, 36, 16),
  List(20, 73,35,29,78,31, 90, 01, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57, 05, 54),
  List(01, 70,54,71,83,51, 54, 69, 16, 92, 33, 48, 61, 43, 52, 01, 89, 19, 67, 48)
)

def isInBounds(x: Int, y: Int) =  y >= 0 && y < table.length && x >= 0 && x < table(y).length

def product(x: Int, y: Int, dx: Int, dy: Int, n: Int): Int = {
  if (!isInBounds(x + (n - 1) * dx, y + (n - 1) * dy))
    return -1

  var prod: Int = 1
  var mx = x
  var my = y
  for(i <- 0 until n) {
    prod *= table(my)(mx)
    mx += dx
    my += dy
  }

  prod
}

def maxProduct(dx: Int, dy: Int): Int = {
  val products = for {
    y <- 0 until table.length
    x <- 0 until table(y).length
  } yield product(x, y, dx, dy, 4)

  products.max
}

Seq(maxProduct(1, 0), maxProduct(0, 1), maxProduct(1, 1), maxProduct(1, -1)).max