Add Border

Elixir Add Border

defmodule AddBorder do
  def add_border(picture) do
    border = String.duplicate("*", String.length(hd(picture)))
    wrapped = Enum.map(picture, fn row -> "*" <> row <> "*" end)

    [border] ++ wrapped ++ [border]
  end
end

This builds a new grid with a * border around every side. It adds a full top and bottom row, then wraps each existing row from left and right.