Re: STL list unique elements efficiency
On 2008-09-20 08:23, Kannan wrote:
Hi,
I have a question about efficiency of some combination of STL
functions. By efficiency I mean faster, memory consumption is not a
problem for my application.
For the list container to create a list with unique elements, is it
more efficient to do a find() if not found then push_back() Or
push_back() anyway then do a sort() followed by unique() ?
Create the list sorted to begin with.
std::list<int> list;
void insert(int const i)
{
std::list<int>::iterator it;
it = std::lower_bound(list.begin(), list.end(), i);
if (i == *it)
// Item already in list
else
list.insert(it, i); // Insert i in sorted order
}
Another question, when I am doing a find() on a list container, is
there any efficiency advantage if the list has unique only elements?
No, but you know you have found the only element if the list contains
only unique items, if it does not you have to use find several times
until you find no more items.
--
Erik Wikstr??m
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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