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[Caml-list] Set and Map question
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Date: | 2004-09-20 (03:52) |
From: | Brian Hurt <bhurt@s...> |
Subject: | Re: [Caml-list] Re: Set and Map question |
On Sun, 19 Sep 2004, Seth Fogarty wrote: > Beh, sorry, I was very confused and asked the wrong questions. The > answer to the below is yes, as specified in the manual, and I knew > that. Too many things juggling at once. > > What I MEANT to ask is: Is there a O(n) method of set/map construction > from a list, as opposed to the O(n log n) fold method. Implemented? No. Possible? Yes, if the list is sorted. The code is actually fairly easy. Take the length of the list. Subtract one for the root node. The first (n-1)/2 elements are in the left hand subtree, the last n-1-((n-1)/2) elements are in the right subtree. If the list isn't sorted, then no. Any algorithm for turning the list into a sorted tree in less than O(N log N) would also serve for sorting the list in less than O(N log N), and would be a major advance in computer science. I don't think it's possible, however. -- "Usenet is like a herd of performing elephants with diarrhea -- massive, difficult to redirect, awe-inspiring, entertaining, and a source of mind-boggling amounts of excrement when you least expect it." - Gene Spafford Brian ------------------- 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