#!/usr/local/bin/ruby

class Graph
  attr :vertices
  attr :edges

  def initialize(vertices = [], edges = Hash.new {|h, k| h[k] = Hash.new {0} })
    @vertices = vertices
    @edges = edges
  end
end

def grow(graph, a, b)
  vertices = graph.vertices.dup
  edges = graph.edges.dup

  vertices << vertices.size

  edges[a][b] += 1
  edges[b][a] += 1

  Graph.new(vertices, edges)
end

g = Graph.new([0, 1])
p g
p grow(g, 0, 1)