hamamatsu.rb #58 のお題を解いた（Scala）

hamamatsu-rb-58.scala

// http://jukensansu.cocolog-nifty.com/planet/2015/11/post-0b4b.html
// parser combinators とか使えそうな気もするけど分からん
def arrayToDigit(ary: List[Int]): Int = {
  ary(0) * 100 + ary(1) * 10 + ary(2)
}

def calcSum(ary: List[Int]): Int = {
  List(ary.slice(0, 3), ary.slice(2, 5), ary.slice(4, 7), ary.slice(6, 8) :+ ary(0)).map(arrayToDigit).sum
}

(1 to 8).toList.permutations.filter(ary => calcSum(ary) == 1725).take(1).foreach { l =>
  println(s"${l(1)}, ${l(3)}, ${l(5)}, ${l(7)}")
}