Data commit

Task/Hailstone-sequence/Kotlin/hailstone-sequence.kotlin

@@ -0,0 +1,24 @@
+import java.util.ArrayDeque
+
+fun hailstone(n: Int): ArrayDeque<Int> {
+    val hails = when {
+        n == 1 -> ArrayDeque<Int>()
+        n % 2 == 0 -> hailstone(n / 2)
+        else -> hailstone(3 * n + 1)
+    }
+    hails.addFirst(n)
+    return hails
+}
+
+fun main(args: Array<String>) {
+    val hail27 = hailstone(27)
+    fun showSeq(s: List<Int>) = s.map { it.toString() }.reduce { a, b -> a + ", " + b }
+    println("Hailstone sequence for 27 is " + showSeq(hail27.take(3)) + " ... "
+            + showSeq(hail27.drop(hail27.size - 3)) + " with length ${hail27.size}.")
+
+    var longestHail = hailstone(1)
+    for (x in 1..99999)
+        longestHail = arrayOf(hailstone(x), longestHail).maxBy { it.size } ?: longestHail
+    println("${longestHail.first} is the number less than 100000 with " +
+            "the longest sequence, having length ${longestHail.size}.")
+}