Breadth first search algorithm with elixir

bfs.exs

defmodule BFS do
  @moduledoc """
  Breadth first search algorithm

  Example

    vertices = %{
      0 => [1, 3],
      1 => [0, 2],
      2 => [1, 3],
      3 => [2]
    }

    BFS.perform(0, 3, vertices)
    "Vertex 3"
    "Vertex 1"
    "Vertex 0"
    true
  """
  @spec perform(integer(), integer(), map()) :: boolean()
  def perform(source, destination, vertices) do
    visited = MapSet.new()
    visited = MapSet.put(visited, source)
    queue = [source]

    recursive(destination, vertices, visited, queue)
  end

  defp recursive(destination, vertices, visited, queue) do
    vertex = List.last(queue)

    result =
      cond do
        is_nil(vertex) ->
          false

        vertex == destination ->
          true

        true ->
          {_, queue} = List.pop_at(queue, -1)

          adjacency_vertices = Enum.filter(vertices[vertex], &(not MapSet.member?(visited, &1)))

          visited =
            Enum.reduce(adjacency_vertices, visited, fn adjacency, acc ->
              MapSet.put(acc, adjacency)
            end)

          queue =
            Enum.reduce(adjacency_vertices, queue, fn adjacency, acc ->
              [adjacency | acc]
            end)

          recursive(destination, vertices, visited, queue)
      end

    IO.inspect("Vertex #{vertex}")
    result
  end
end