Initial data commit

Task/Stream-merge/Elixir/stream-merge.elixir

@@ -0,0 +1,29 @@
+defmodule StreamMerge do
+  def merge2(file1, file2), do: mergeN([file1, file2])
+
+  def mergeN(files) do
+    Enum.map(files, fn fname -> File.open!(fname) end)
+    |> Enum.map(fn fd -> {fd, IO.read(fd, :line)} end)
+    |> merge_loop
+  end
+
+  defp merge_loop([]), do: :ok
+  defp merge_loop(fdata) do
+    {fd, min} = Enum.min_by(fdata, fn {_,head} -> head end)
+    IO.write min
+    case IO.read(fd, :line) do
+      :eof -> File.close(fd)
+              List.delete(fdata, {fd, min}) |> merge_loop
+      head -> List.keyreplace(fdata, fd, 0, {fd, head}) |> merge_loop
+    end
+  end
+end
+
+filenames = ~w[temp1.dat temp2.dat temp3.dat]
+Enum.each(filenames, fn fname ->
+  IO.puts "#{fname}: " <> File.read!(fname) |> String.replace("\n", " ")
+end)
+IO.puts "\n2-stream merge:"
+StreamMerge.merge2("temp1.dat", "temp2.dat")
+IO.puts "\nN-stream merge:"
+StreamMerge.mergeN(filenames)