I want to write a generic quicksort over STL containers. We have to
parallelize this algorithm afterwards. This is what I've got for now:
template<typena me containerIterat or>
void quicksort(conta inerIterator begin, containerIterat or end){
Â*Â*Â*Â*Â*Â*Â*Â *ifÂ*(endÂ*>Â*b egin){
Â*Â*Â*Â*Â*Â*Â*Â *Â*Â*Â*Â*Â*Â*Â* Â*containerIter atorÂ*pivot(beg in);
Â*Â*Â*Â*Â*Â*Â*Â *Â*Â*Â*Â*Â*Â*Â* Â*containerIter atorÂ*newPivot( partition(begin ,Â*end,Â*pivot) );
Â*Â*Â*Â*Â*Â*Â*Â *Â*Â*Â*Â*Â*Â*Â* Â*quicksort(beg in,Â*--newPivot);
Â*Â*Â*Â*Â*Â*Â*Â *Â*Â*Â*Â*Â*Â*Â* Â*quicksort(++n ewPivot,Â*end);
Â*Â*Â*Â*Â*Â*Â*Â *}
}
template<typena me containerIterat or>
containerIterat or partition(conta inerIterator begin, containerIterat or end,
containerIterat or pivot){
Â*Â*Â*Â*Â*Â*Â*Â *//whatÂ*IÂ*wantÂ* hereÂ*isÂ*toÂ*s toreÂ*theÂ*valu eÂ*ofÂ*theÂ*piv ot,
Â*Â*Â*Â*Â*Â*Â*Â *//soÂ*somethingÂ* like:Â*
Â*Â*Â*Â*Â*Â*Â*Â *pivotValue(*pi vot);
}
Problem is I don't know the type of this value at this stage.
Should I include it in the templateparamet ers?
3  2407 
"Lieven" <li************ *@hotmail.com> wrote in message
news:41******** **************@ news.skynet.be. .. pivotValue(*piv ot);
}
Problem is I don't know the type of this value at this stage.
Should I include it in the templateparamet ers?
No need. If T is an iterator type, then std::iterator_t raits<T>::value _type
is the type that is obtained by dereferencing T.
"Andrew Koenig" <ar*@acm.org> wrote in message
news:Vi******** *************@b gtnsc04-news.ops.worldn et.att.net... "Lieven" <li************ *@hotmail.com> wrote in message
news:41******** **************@ news.skynet.be. ..
pivotValue(*piv ot);
}
Problem is I don't know the type of this value at this stage.
Should I include it in the templateparamet ers?
No need. If T is an iterator type, then
std::iterator_t raits<T>::value _type is the type that is obtained by
dereferencing T.
And 'iterator type' includes pointers.
john
Lieven wrote: I want to write a generic quicksort over STL containers. We have to
parallelize this algorithm afterwards. This is what I've got for now:
template<typena me containerIterat or>
void quicksort(conta inerIterator begin, containerIterat or end){
ifÂ*(endÂ*>Â*be gin){
containerIterat orÂ*pivot(begin );
containerIterat orÂ*newPivot(pa rtition(begin, *end,Â*pivot));
/*I realize I made a mistake here. When I do --newPivot, this is a
destructive operation. The iterator now points to the element in front of
the pivotelement. So the ++newPivot afterwards just points to the
pivotelement again.*/
quicksort(begin ,Â*--newPivot);
quicksort(++new Pivot,Â*end);
}
}
template<typena me containerIterat or>
containerIterat or partition(conta inerIterator begin, containerIterat or
end, containerIterat or pivot){
//whatÂ*IÂ*wantÂ* hereÂ*isÂ*toÂ*s toreÂ*theÂ*valu eÂ*ofÂ*theÂ*piv ot,
//soÂ*somethingÂ* like:
pivotValue(*piv ot);
}
Problem is I don't know the type of this value at this stage.
Should I include it in the templateparamet ers?
What is the best way to solve this? something like using --newPivot++ in the
first expression? Or is there another way? This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
by: why |
last post by:
Hi,
just been curious. i have learn that quicksorting algorithm is more
widely used then heapsort, despite having the same performance
indication of O(n log n)
anyone knows why?
newbie
|
by: Lieven |
last post by:
I want to make a quicksort algorithm that can take both a vector and a list.
This is the code I've got. But I also want to give an argument that will be
used for comparing the elements. I am used to programming in Lisp/Scheme,
where I would just pass a lambda. Is a function object something like that
in C++? And in that case, how would I pass the function/operator < (lesser
then).
//quicksort
template<typename BidirectionalIterator>...
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by: HERC777 |
last post by:
just paste the below into notepad, call it iqsort.html double click it
and your IE browser will run it. (neat! a universal programming
language we can all run!)
it falls out from the sort procedure. I got javascript quicksort
running, it's quick but it gets stack overflow after about 5000
elements.
Am I passing the array as a parameter alright? I think javascript
default is to pass pointers, that can be global.
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Hey,
Here is the pseudocode of quicksort. It can be observed that there
are as many as (n-1) unresolved stack calls in the worst case. Now, how
do i reduce this unresolved stack calls? what modifications should I
make?
procedure QuickSort(L, low, high) recursive
Input: L (a list of size n), low, high (integers)
Output: L is sorted
if high > low then
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a problem and needs to close". When there is no zeros in the integer
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The pivot is always the last element. Try to change the last element in
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Does anyone know how to make quicksort for single linked list without
using array?
I know that mergesort is maybe better but I need quicksort!!
thnx
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by: aparnakakkar2003 |
last post by:
hello
can any one tell me how i can create program to sort string
list(standard template library) using quicksort.
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last post by:
hello
can any one tell me how i can create program to sort string
list(standard template library) using quicksort.
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