5.6.rb

def check_cycle(graph,node,connected)
  counter =0

  return false if graph[node].nil?
  graph[node].each do |element|
    if connected.include?(element)
      counter +=1
      return true  if counter ==2
    else
      connected<< element
      return true if check_cycle(graph,element,connected)
    end
  end
  false
end
def graph_cycle?(graph)
  # write your code here
  check_cycle(graph,0,[0])
end
puts graph_cycle?({
  0=>[2], 
  1=>[4], 
  2=>[0, 5, 3], 
  3=>[5, 2], 
  4=>[5, 1], 
  5=>[4, 2, 3]
})
# => true
puts graph_cycle?({
  0=>[2], 
  1=>[2], 
  2=>[0, 1, 3, 4, 5], 
  3=>[2], 
  4=>[2]
})
# => false