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Java HashMap performance optimization / alternative
...={99,100}) will hash to the same value as (a[]={3,1,2}, b[]={100,99}). Actually all keys k1 and k2 where sum(k1.a)==sum(k2.a) and sum(k1.b)=sum(k2.b) will result in collisions. I suggest assigning a weight to each position of the array:
hash = hash * 5381 + (c0*a[0] + c1*a[1]);
hash = hash * 5381 +...
Diff files present in two different directories
I have two directories with the same list of files. I need to compare all the files present in both the directories using the diff command. Is there a simple command line option to do it, or do I have to write a shell script to get the file listing and then iterate through them?
...
How do I determine the size of my array in C?
...
It should be the case with all compilers, since the results of sizeof is defined as a compile-time constant.
– Mark Harrison
Sep 22 '13 at 5:39
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Why is address zero used for the null pointer?
...emory, because it means freeing the pointer again isn't dangerous; when I call malloc it returns a pointer with the value zero if it can't get me memory; I use if (p != 0) all the time to make sure passed pointers are valid, etc.
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What are “res” and “req” parameters in Express functions?
...red
request.method, which will be "GET" in this case, hence the app.get() call.
An array of HTTP headers in request.headers, containing items like request.headers.accept, which you can use to determine what kind of browser made the request, what sort of responses it can handle, whether or not it's a...
Difference between Pragma and Cache-Control headers?
... Cache-Control: no-cache has the same meaning for requests but is actually also defined for responses, meaning "If you want to use a cached copy of this in future, you must first check with me that it is up-to-date (i.e. perform revalidation)".
– clime
Mar...
Specify width in *characters*
... than the width. Same holds for ex, which is the height of an x. More generally speaking, these are the heights of uppercase and lowercase letters.
Width is a totally different issue....
Change your example above to
<div>
<span>1</span> 3 5 7 9 1 3 5 7 9 1
</div>
an...
What are the relative strengths and weaknesses of Git, Mercurial, and Bazaar? [closed]
...ike that very much.
Bazaar is reasonably fast (very fast for trees with shallow history, but presently scales poorly with history length), and is easy-to-learn to those familiar with the command-line interfaces of traditional SCMs (CVS, SVN, etc). Win32 is considered a first-class target by its dev...
What is a lambda expression in C++11?
... }
} f;
std::for_each(v.begin(), v.end(), f);
}
however this is not allowed, f cannot be passed to a template function in C++03.
The new solution
C++11 introduces lambdas allow you to write an inline, anonymous functor to replace the struct f. For small simple examples this can be cleaner t...
Drag and drop files into WPF
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This is basically what you want to do.
private void ImagePanel_Drop(object sender, DragEventArgs e)
{
if (e.Data.GetDataPresent(DataFormats.FileDrop))
{
// Note that you can have more than one file.
string[] files = (string[...