refactored_markov_chain.rb

class MarkovChain
  def initialize(states, transitions=nil)
    @states = states
    @graph = empty_graph
    @transitions = build_transitions(transitions) if transitions
  end

  def transitions=(transitions)
    @graph = empty_graph
    @transitions = build_transitions(transitions) if transitions
  end

  private

  def build_transitions(transitions)
    count_transitions transitions
    normalize transitions
  end
end