crypto-square

elixir/crypto-square/lib/crypto_square.ex

@@ -19,13 +19,17 @@ defmodule CryptoSquare do
     |> String.replace(~r/[^a-z0-9]/, "")
   end
 
+  defp square(""), do: ""
+
   defp square(str) do
     length = String.length(str)
-    row = :math.ceil(length ** 0.5)
-    col = :math.ceil(length / row)
+    row = round(ceil(length ** 0.5))
 
     str
     |> String.split("", trim: true)
-    |> Enum.chunk_every(col, col)
+    |> Enum.chunk_every(row, row, List.duplicate(" ", row))
+    |> Enum.zip()
+    |> Enum.map(&Tuple.to_list(&1))
+    |> Enum.map_join(" ", &Enum.join(&1))
   end
 end