"xyz" <lavanyareddy.p@gmail.com> wrote in message
news:20e412b2-8666-40af-b3ae-44b543da933b@b1g2000hsg.googlegroups.com...
On Jul 4, 11:44 am, James Kanze <james.ka...@gmail.com> wrote:
> On Jul 3, 1:30 pm, "Duane Hebert" <s...@flarn2.com> wrote:
>
> > "James Kanze" <james.ka...@gmail.com> wrote in message
> >news:40e49767-091e-406d-92c0-9d0f42f24a08@b1g2000hsg.googlegroups.com...
> > >With a good hashing function, look up in a hash table is O(1).
> > >With something like 2 million entries, the difference between
> > >O(ln n) and O(1) can be significant. (In my own tests, hash
> > >tables beat std::map or a sorted factor by a ratio of two to one
> > >for 1200 entries, and almost five to one for a million entries.)
> > True but he's saying that his code is bottlenecked in the
> > search but then if the object isn't found, he's pushing it
> > into a vector. It's not clear if it's the same vector.
>
> It's not clear at all what he does if he don't find the element.
> (At one point, he says something about a "new" vector, but I'm
> not sure what he's doing with it.)
>
> > If it is and he needs to keep it sorted, inserting in the
> > middle of the vector may offset any value from the hash table.
>
> I'm afraid I don't understand. The hash table contains the
> elements he's comparing against. Depending on what he's doing
> he may want to insert the element he didn't find into the hash
> table, or he may not. There's been no indication of having to
> keep any sort of order (or at least, I didn't see it).
>
> --
> James Kanze (GABI Software) email:james.ka...@gmail.com
> Conseils en informatique orientée objet/
> Beratung in objektorientierter Datenverarbeitung
> 9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34

-------

> I already cleared about this point in the post...
>
> I check every incoming element the vector1...if it matches in one of
> the element in the vector1 I collect the statistics...
> after certain timeout the entreis get deleted...in vector1...the
> timeout for every entry in the vector veries.
> suppose if my entry doesnt match any of the entreis in vector1 i store
> it in other vector for eg namely vector2
> and these entreis i export to other module...and it does something
> with those entries
>
> as i get high timeouts my vectors are very large...so the incoming
> element needs to check all those entries whether it is matched in the
> vector or not..so i asked whether it is better to use vectors or
> maps...
> thats all...thanks everyone...
> hope everyone understand....

Have you followed the thread so far? You should have enough information to
decide which to at least try. Most likely you will want to try a sorted
vector, a hash map/set and see which is better for you. You have not stated
how/when entries would get added to vector1. If entries *never* get added,
the a sorted vector would definately be the way to go. Read your vector1 at
the beginning, sort it. Instead of deleting the entries after timeout,
however, I would probalby mark it as delted somehow (just so I wouldn't have
to resort my vector).

If you add entries to vector1 periodically, then maybe a sorted vector would
still be the way to go, or a binary tree (map/set/hashmap, whatever). It
depends on how often you insert entries, etc... An unsorted vector is
defintely NOT the way to go, however. Worst case scenario.