Data commit

Task/Stream-merge/Scala/stream-merge-1.scala

@@ -0,0 +1,20 @@
+def mergeN[A : Ordering](is: Iterator[A]*): Iterator[A] = is.reduce((a, b) => merge2(a, b))
+
+def merge2[A : Ordering](i1: Iterator[A], i2: Iterator[A]): Iterator[A] = {
+  merge2Buffered(i1.buffered, i2.buffered)
+}
+
+def merge2Buffered[A](i1: BufferedIterator[A], i2: BufferedIterator[A])(implicit ord: Ordering[A]): Iterator[A] = {
+  if (!i1.hasNext) {
+    i2
+  } else if (!i2.hasNext) {
+    i1
+  } else {
+    val nextHead = if (ord.lt(i1.head, i2.head)) {
+      Iterator.single(i1.next)
+    } else {
+      Iterator.single(i2.next)
+    }
+    nextHead ++ merge2Buffered(i1, i2)
+  }
+}

Task/Stream-merge/Scala/stream-merge-2.scala

@@ -0,0 +1,24 @@
+val i1 = Iterator.tabulate(5) { i =>
+  val x = i * 3
+  println(s"generating $x")
+  x
+}
+
+val i2 = Iterator.tabulate(5) { i =>
+  val x = i * 3 + 1
+  println(s"generating $x")
+  x
+}
+
+val i3 = Iterator.tabulate(5) { i =>
+  val x = i * 3 + 2
+  println(s"generating $x")
+  x
+}
+
+val merged = mergeN(i1, i2, i3)
+
+while (merged.hasNext) {
+  val x = merged.next
+  println(s"output: $x")
+}