Initial data commit

Task/Fibonacci-sequence/Scala/fibonacci-sequence-1.scala

@@ -0,0 +1,5 @@
+def fib(i: Int): Int = i match {
+  case 0 => 0
+  case 1 => 1
+  case _ => fib(i - 1) + fib(i - 2)
+}

Task/Fibonacci-sequence/Scala/fibonacci-sequence-2.scala

@@ -0,0 +1 @@
+lazy val fib: LazyList[Int] = 0 #:: 1 #:: fib.zip(fib.tail).map { case (a, b) => a + b }

Task/Fibonacci-sequence/Scala/fibonacci-sequence-3.scala

@@ -0,0 +1,6 @@
+import scala.annotation.tailrec
+@tailrec
+final def fib(x: Int, prev: BigInt = 0, next: BigInt = 1): BigInt = x match {
+  case 0 => prev
+  case _ => fib(x - 1, next, next + prev)
+}

Task/Fibonacci-sequence/Scala/fibonacci-sequence-4.scala

@@ -0,0 +1,13 @@
+// Fibonacci using BigInt with LazyList.foldLeft optimized for GC (Scala v2.13 and above)
+// Does not run out of memory for very large Fibonacci numbers
+def fib(n: Int): BigInt = {
+
+  def series(i: BigInt, j: BigInt): LazyList[BigInt] = i #:: series(j, i + j)
+
+  series(1, 0).take(n).foldLeft(BigInt("0"))(_ + _)
+}
+
+// Small test
+(0 to 13) foreach {n => print(fib(n).toString + " ")}
+
+// result: 0 1 1 2 3 5 8 13 21 34 55 89 144 233

Task/Fibonacci-sequence/Scala/fibonacci-sequence-5.scala

@@ -0,0 +1,6 @@
+val it: Iterator[Int] = Iterator.iterate((0, 1)) { case (a, b) => (b, a + b) }.map(_._1)
+
+def fib(n: Int): Int = it.drop(n).next()
+
+// example:
+println(it.take(13).mkString(",")) // prints: 0,1,1,2,3,5,8,13,21,34,55,89,144