]> On Saturday 07 December 2002 05:28 am, Xavier Leroy wrote: > > If the given list has L elements, each with S items, then flatten should > > O((L*S)*L) = O(S*L^2) time, since you have to keep on churning through > > every single element in the ever-expanding l at every recursive flatten > > call. That's too bad. > > Here's an experiment I tried: > > [...] > > I guess it looks linear because of the small input size. > > It's always a good idea to do experimental measurements to confirm a > complexity analysis, just to make sure you haven't goofed. But when > the measurements disagree with the analysis, you're supposed to go > back to the analysis and find the flaw in it, not discard the > experiment :-) > > More seriously: l1 @ l2 takes time O(length(l1)); the length of l2 > doesn't matter since l2 isn't copied. This gives List.flatten a > complexity of O(S*L) in your example (list of length L, each list > element being of length S). You are right. I had the incorrect mental picture of (@) being called with the increasingly large first argument: S + 2*S +... + (L-1)*S = O(S*L^2). Cheers Oleg > This is optimal for immutable, > singly-linked lists. > > - Xavier Leroy ------------------- To unsubscribe, mail caml-list-request@inria.fr Archives: http://caml.inria.fr Bug reports: http://caml.inria.fr/bin/caml-bugs FAQ: http://caml.inria.fr/FAQ/ Beginner's list: http://groups.yahoo.com/group/ocaml_beginners