Yellowstone sequence: Difference between revisions

=={{header|Scala}}==

{{trans|Java}}

<syntaxhighlight lang="Scala">

import scala.util.control.Breaks._

object YellowstoneSequence extends App {

println(s"First 30 values in the yellowstone sequence:\n${yellowstoneSequence(30)}")

def yellowstoneSequence(sequenceCount: Int): List[Int] = {

var yellowstoneList = List(1, 2, 3)

var num = 4

var notYellowstoneList = List[Int]()

while (yellowstoneList.size < sequenceCount) {

val foundIndex = notYellowstoneList.indexWhere(test =>

gcd(yellowstoneList(yellowstoneList.size - 2), test) > 1 &&

gcd(yellowstoneList.last, test) == 1

)

if (foundIndex >= 0) {

yellowstoneList = yellowstoneList :+ notYellowstoneList(foundIndex)

notYellowstoneList = notYellowstoneList.patch(foundIndex, Nil, 1)

} else {

breakable({

while (true) {

if (gcd(yellowstoneList(yellowstoneList.size - 2), num) > 1 &&

gcd(yellowstoneList.last, num) == 1) {

yellowstoneList = yellowstoneList :+ num

num += 1

// break the inner while loop

break

}

notYellowstoneList = notYellowstoneList :+ num

num += 1

}

});

}

}

yellowstoneList

}

def gcd(a: Int, b: Int): Int = if (b == 0) a else gcd(b, a % b)

}

</syntaxhighlight>

{{out}}

<pre>

First 30 values in the yellowstone sequence:

List(1, 2, 3, 4, 9, 8, 15, 14, 5, 6, 25, 12, 35, 16, 7, 10, 21, 20, 27, 22, 39, 11, 13, 33, 26, 45, 28, 51, 32, 17)

</pre>