27 lines
1.0 KiB
Scala
27 lines
1.0 KiB
Scala
object HailstoneSequence extends App { // Show it all, default number is 27.
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def hailstone(n: Int): LazyList[Int] =
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n #:: (if (n == 1) LazyList.empty else hailstone(if (n % 2 == 0) n / 2 else n * 3 + 1))
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Hailstone.details(args.headOption.map(_.toInt).getOrElse(27))
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HailTest.main(Array())
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}
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object Hailstone extends App { // Compute a given or default number to Hailstone sequence
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def details(nr: Int): Unit = {
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val collatz = HailstoneSequence.hailstone(nr)
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println(s"Use the routine to show that the hailstone sequence for the number: $nr.")
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println(collatz.toList)
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println(s"It has ${collatz.length} elements.")
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}
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details(args.headOption.map(_.toInt).getOrElse(27))
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}
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object HailTest extends App { // Compute only the < 100000 test
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println(
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"Compute the number < 100,000, which has the longest hailstone sequence with that sequence's length.")
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val (n, len) = (1 until 100000).map(n => (n, HailstoneSequence.hailstone(n).length)).maxBy(_._2)
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println(s"Longest hailstone sequence length= $len occurring with number $n.")
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}
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