Find Hamiltonian cycle algorithm with Elixir

find_hamiltonian_cycle.exs

defmodule HamiltonianCycle do
  @moduledoc """
  Find Hamiltonian cycle algorithm

  Example

    vertices = %{
      0 => [1, 2],
      1 => [0, 2, 3],
      2 => [0, 1, 4],
      3 => [1, 4],
      4 => [2, 3]
    }

    HamiltonianCycle.perform(vertices)
    "Vertex 3"
    "Vertex 4"
    "Vertex 2"
    "Vertex 1"
    "Vertex 0"
    true
  """
  def perform(vertices) do
    recursive(0, vertices)
  end

  defp recursive(vertex, vertices, visited \\ MapSet.new()) do
    adjacency_vertices = vertices[vertex]

    total_vertices = Map.keys(vertices)

    has_hamiltonian_cycle =
      MapSet.size(visited) == length(total_vertices) - 1 and adjacency_vertices != []

    result =
      if has_hamiltonian_cycle do
        true
      else
        visited = MapSet.put(visited, vertex)

        adjacency_vertices
        |> Enum.filter(&(not MapSet.member?(visited, &1)))
        |> Enum.reduce_while(false, fn adjacency, _acc ->
          result = recursive(adjacency, vertices, visited)

          if result do
            {:halt, true}
          else
            {:cont, false}
          end
        end)
      end

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