class LinkedListNode

attr_accessor :value, :next_node

  def initialize(value, next_node=nil)
    @value = value
    @next_node = next_node
  end

end



def reverse_list(list, previous=nil)
x=0

  while list
    temp = list.next_node
    list.next_node = previous
    previous = list

    list = temp


    newhead = previous

    x = x + 1
  end
  return newhead
end

def print_values(list_node)
    if list_node
      print "#{list_node.value} --> "
      print_values(list_node.next_node)
    else
      print "nil\n"
      return
    end
end


node1 = LinkedListNode.new(37)
node2 = LinkedListNode.new(99, node1)
node3 = LinkedListNode.new(12, node2)


print_values(node3)

puts "-------"

revlist = reverse_list(node3)

print_values(revlist)