linked_list2.rb

class LinkedListNode
  attr_accessor :value, :next_node

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

class Stack
  attr_reader :data

  def initialize 
    @data = nil
  end

  def push(value)
    @data = LinkedListNode.new(value)
  end

  def pop
    node_value = @data.value
    @data = @data.next_node

    return node_value
  end

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

def reverse_list(list, previous=nil)
  while list != nil
    old_list = list.next_node
    list.next_node = previous
    previous = list
    list = old_list
  end
  return previous
end


n1 = LinkedListNode.new(37)
n2 = LinkedListNode.new(99, n1)
n3 = LinkedListNode.new(12, n2)


print_values(n3)
reverse = reverse_list(n3)
print_values(reverse)