add P02_Impl PenultimatElement

src/com/concept/scala/NinetyNineProblems/P02_Impl.scala

@@ -0,0 +1,32 @@
+package com.concept.scala.NinetyNineProblems
+
+import scala.annotation.tailrec
+
+/**
+ *
+ *
+ * @see P02
+ * @example penultimate(List(1, 1, 2, 3, 5, 8))
+ * res0: Int = 5
+ * @groupname Problem - 3
+ *
+ */
+
+class P02_Impl extends PenultimatElement {
+ override def penultimatElement_builtin[T](list: List[T]): T = if (list.nonEmpty) list.init.last else throw new NoSuchElementException
+
+ @tailrec
+ final override def penultimatElement_recursive[T](list: List[T]): T =
+ list match {
+ case penultimatElement :: lastElement :: Nil => penultimatElement
+ case head :: tail => penultimatElement_recursive(tail)
+ case _ => throw new NoSuchElementException
+ }
+
+}
+
+trait PenultimatElement {
+ def penultimatElement_builtin[T](list: List[T]): T
+
+ def penultimatElement_recursive[T](list: List[T]): T
+}