Add Quick Sort in Elixir

Author: ricardomaps

archive/e/elixir/quick-sort.ex

@@ -0,0 +1,37 @@
+defmodule QuickSort do
+  @doc """
+  Sorts a list of integers in ascending order using the quicksort algorithm.
+  """
+  @spec quick_sort(list :: list(integer())) :: list(integer())
+  def quick_sort([]), do: []
+
+  def quick_sort([x | xs]) do
+    {left, right} = Enum.split_with(xs, &(&1 < x))
+    quick_sort(left) ++ [x] ++ quick_sort(right)
+  end
+
+  @spec parse_list(str :: String.t()) :: {:ok, list(integer())} | :error
+  def parse_list(""), do: :error
+
+  def parse_list(str) do
+    str
+    |> String.split(",")
+    |> Enum.map(&String.trim/1)
+    |> Enum.reduce_while({:ok, []}, fn n, {:ok, acc} ->
+      case Integer.parse(n) do
+        {n, ""} -> {:cont, {:ok, [n | acc]}}
+        _ -> {:halt, :error}
+      end
+    end)
+  end
+end
+
+with [arg] <- System.argv(),
+     {:ok, [_, _ | _] = list} <- QuickSort.parse_list(arg) do
+  QuickSort.quick_sort(list) |> Enum.join(", ") |> IO.puts()
+else
+  _ ->
+    IO.puts(
+      "Usage: please provide a list of at least two integers to sort in the format \"1, 2, 3, 4, 5\""
+    )
+end