Re: about new and delete

From:
SG <s.gesemann@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Tue, 29 Sep 2009 00:34:43 -0700 (PDT)
Message-ID:
<abc539b6-a8ab-4932-9424-79ad90c39a17@a7g2000yqo.googlegroups.com>
Sam wrote:

Juha Nieminen writes:

And what is the complexity of removing an element from the middle of t=

he

list, versus the middle of a vector?


O(n) for both.


Hahahahahaha.

std::list<obj> theList;

// =85

std::list<obj>::iterator p;

// =85

theList.erase(p); // Warning, O(n)!!!!!

Very funny.

                  If you want to prove me wrong, writ=

e a function which

takes a std::list as parameter and removes the element at the exact
middle faster than O(n).


What you fail to grok, is that when you have a member of containe that yo=

u

want removed, you already have its iterator, you don't need to search for
it.


Who said something about "having a member"?

Thank you for playing.


*yawn*

You simply phrased your question badly, Sam. It's not obvious if an
iterator to the middle element is already known. I do think you're
smart enough to grok what was going on. Juha even explained how he
interpreted the question by saying "write a function which takes a
std::list as parameter and removes the element at the exact middle
faster than O(n)". But instead of saying something like

  "Yes, O(n) if you don't know the iterator. But I was assuming
   that it is known. In that case std::list makes a difference."

you try to make it look like you're the only sane person here.
-1 for weak communication skills.

Cheers,
SG

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