RosettaCodeData/Task/Damm-algorithm/Scala/damm-algorithm.scala

30 lines
886 B
Scala

import scala.annotation.tailrec
object DammAlgorithm extends App {
private val numbers = Seq(5724, 5727, 112946, 112949)
@tailrec
private def damm(s: String, interim: Int): String = {
def table =
Vector(
Vector(0, 3, 1, 7, 5, 9, 8, 6, 4, 2),
Vector(7, 0, 9, 2, 1, 5, 4, 8, 6, 3),
Vector(4, 2, 0, 6, 8, 7, 1, 3, 5, 9),
Vector(1, 7, 5, 0, 9, 8, 3, 4, 2, 6),
Vector(6, 1, 2, 3, 0, 4, 5, 9, 7, 8),
Vector(3, 6, 7, 4, 2, 0, 9, 5, 8, 1),
Vector(5, 8, 6, 9, 7, 2, 0, 1, 3, 4),
Vector(8, 9, 4, 5, 3, 6, 2, 0, 1, 7),
Vector(9, 4, 3, 8, 6, 1, 7, 2, 0, 5),
Vector(2, 5, 8, 1, 4, 3, 6, 7, 9, 0)
)
if (s.isEmpty) if (interim == 0) "✔" else "✘"
else damm(s.tail, table(interim)(s.head - '0'))
}
for (number <- numbers) println(f"$number%6d is ${damm(number.toString, 0)}.")
}