# This linked list reversal does not involve a stack, it simply
#creates a new set of nodes that point the opposite direction.

class LinkedListNode
  attr_accessor :value, :next_node

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


def reverse_list(node, previous=nil)
  return if node.nil?
  @head = LinkedListNode.new(node.value, previous)
  reverse_list(node.next_node, @head)
  return @head
end


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