reversed_linked_list

class LinkedListNode
  attr_accessor :value, :next_node
 
  def initialize(value, next_node=nil)
    @value = value
    @next_node = next_node
  end
end

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

class Stack
    attr_reader :data
    
    def initialize
        @data = nil
    end

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

    def pop
        result = @data.value
        @data = @data.next_node
        return result
    end

end

def reverse_list(list)
    stack = Stack.new()

    while list
        stack.push(list.value)
        list = list.next_node
    end

    return stack.data
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)