25 lines
868 B
Kotlin
25 lines
868 B
Kotlin
import java.util.ArrayDeque
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fun hailstone(n: Int): ArrayDeque<Int> {
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val hails = when {
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n == 1 -> ArrayDeque<Int>()
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n % 2 == 0 -> hailstone(n / 2)
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else -> hailstone(3 * n + 1)
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}
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hails.addFirst(n)
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return hails
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}
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fun main(args: Array<String>) {
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val hail27 = hailstone(27)
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fun showSeq(s: List<Int>) = s.map { it.toString() }.reduce { a, b -> a + ", " + b }
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println("Hailstone sequence for 27 is " + showSeq(hail27.take(3)) + " ... "
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+ showSeq(hail27.drop(hail27.size - 3)) + " with length ${hail27.size}.")
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var longestHail = hailstone(1)
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for (x in 1..99999)
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longestHail = arrayOf(hailstone(x), longestHail).maxBy { it.size } ?: longestHail
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println("${longestHail.first} is the number less than 100000 with " +
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"the longest sequence, having length ${longestHail.size}.")
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}
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