linked list with cycle structure

[Robert Kern]

Terry Reedy wrote:
> David Hláčik wrote:
>> But what if i have another condition , and that is *i can use only
>> helping memory with constant size* ? This means i am not able to
>> create any set and adding elements there. I need to have a constant
>> size variables . This is complication a complication for me.
> 
> Interesting problem.  If it is homework, there must be an answer.

It's also an interview question I've seen reasonably often, particularly with 
that last complication.

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
  that is made terrible by our own mad attempt to interpret it as though it had
  an underlying truth."
   -- Umberto Eco