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Top Forums Programming Improve the performance of my C++ code Post 302931813 by Corona688 on Thursday 15th of January 2015 03:52:31 PM
Old 01-15-2015
Quote:
Originally Posted by yifangt
corona688, can I make sure the difference between list<> and vector <> can be hours?
Vector is not "fast" and list is not "slow".

If you try to insert in arbitrary places anywhere inside a vector, it will be slow.

If you try to use a list for random access, it will be slow.

What I have suggested is better suited for lists than vectors.

Quote:
I must have missed something big for my code.
You are comparing every element to every other element. If you have 300 elements, that's 90,000 comparisons. If you have 3000 elements, that's 9 million comparisons. Any sequence you remove early means 300 fewer loops later.

You are also searching for strings inside strings without using any sort of index, but that would be complicated.

Last edited by Corona688; 01-15-2015 at 04:59 PM..
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lreplace(n)						       Tcl Built-In Commands						       lreplace(n)

__________________________________________________________________________________________________________________________________________________

NAME
lreplace - Replace elements in a list with new elements SYNOPSIS
lreplace list first last ?element element ...? _________________________________________________________________ DESCRIPTION
lreplace returns a new list formed by replacing one or more elements of list with the element arguments. first and last specify the first and last index of the range of elements to replace. 0 refers to the first element of the list, and end (or any abbreviation of it) may be used to refer to the last element of the list. If list is empty, then first and last are ignored. If first is less than zero, it is considered to refer to the first element of the list. For non-empty lists, the element indicated by first must exist. If last is less than zero but greater than first, then any specified elements will be prepended to the list. If last is less than first then no elements are deleted; the new elements are simply inserted before first. The element arguments specify zero or more new arguments to be added to the list in place of those that were deleted. Each element argu- ment will become a separate element of the list. If no element arguments are specified, then the elements between first and last are sim- ply deleted. If list is empty, any element arguments are added to the end of the list. SEE ALSO
list(n), lappend(n), lindex(n), linsert(n), llength(n), lsearch(n), lset(n), lrange(n), lsort(n) | KEYWORDS
element, list, replace Tcl 7.4 lreplace(n)
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