Data update

Task/Yellowstone-sequence/Scala/yellowstone-sequence.scala

@@ -0,0 +1,42 @@
+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)
+}