BFS Implementation. (Not defined as a Class)

bfs.rb

require '../lib/Queue'
frontier = Queue.new
neighbors = {}
neighbors = {:a => [:b,:f],
             :b => [:a,:c,:d],
             :c => [:b,:e], 
             :d => [:b,:e],
             :e => [:c,:d],
             :f => [:a,:g,:h,:i],
             :g => [:f], 
             :h => [:f],
             :i => [:f] 
            }

parent = {}
visited = []


# :a is the source node for BFS search. Put :a into the frontier queue
parent[:a] = nil
frontier.enqueue(:a)

  while !frontier.empty? do
    frontier.each do |node|
      neighbors[node].each do |neighbor|
        if frontier.include?(neighbor) || visited.include?(neighbor)
          next
        else
          frontier.enqueue(neighbor)
          parent[neighbor] = node
        end
      end
    end
    visited << frontier.dequeue

  end