I haven&#x27;t thought about it closely but, from a cursory read, it sounds like the SquareList data structure: <a href="http:&#x2F;&#x2F;www.drdobbs.com&#x2F;database&#x2F;the-squarelist-data-structure&#x2F;184405336" rel="nofollow">http:&#x2F;&#x2F;www.drdobbs.com&#x2F;database&#x2F;the-squarelist-data-structur...</a>