twosum problem with elixir

TwoSum/twoSum.exs

@@ -0,0 +1,23 @@
+# Two sum problem by leetcode: https://leetcode.com/problems/two-sum/description/
+defmodule Solution do
+  @spec two_sum(nums :: [integer], target :: integer) :: [integer]
+  def two_sum(nums, target) do
+    map = nums |> 
+    Enum.with_index |> 
+    Enum.reduce(%{}, fn({n, i}, prev) -> Map.put(prev, n, i) end)
+    nums |>
+    Enum.with_index |>
+    Enum.reduce([], fn({cur_value, i}, prev) -> 
+            if prev === [] do
+                sub = target - cur_value
+                if map[sub] != nil && map[sub] != i do
+                  [i, map[sub]]
+                else
+                    prev
+                end
+            else
+                prev
+            end
+        end)
+  end
+end