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Task/Quickselect-algorithm/Scala/quickselect-algorithm.scala

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+import scala.util.Random
+
+object QuickSelect {
+  def quickSelect[A <% Ordered[A]](seq: Seq[A], n: Int, rand: Random = new Random): A = {
+    val pivot = rand.nextInt(seq.length);
+    val (left, right) = seq.partition(_ < seq(pivot))
+    if (left.length == n) {
+      seq(pivot)
+    } else if (left.length < n) {
+      quickSelect(right, n - left.length, rand)
+    } else {
+      quickSelect(left, n, rand)
+    }
+  }
+
+  def main(args: Array[String]): Unit = {
+    val v = Array(9, 8, 7, 6, 5, 0, 1, 2, 3, 4)
+    println((0 until v.length).map(quickSelect(v, _)).mkString(", "))
+  }
+}