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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 +...
Shell Script — Get all files modified after
...gs tar --no-recursion -czf myfile.tgz
where find . -mtime -1 will select all the files in (recursively) current directory modified day before. you can use fractions, for example:
find . -mtime -1.5 | xargs tar --no-recursion -czf myfile.tgz
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Undefined, unspecified and implementation-defined behavior
... coming from other languages (other languages try to hide it better). Basically, it is possible to write C++ programs that do not behave in a predictable way, even though many C++ compilers will not report any errors in the program!
Let's look at a classic example:
#include <iostream>
int ma...
What is the difference between Bower and npm?
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All package managers have many downsides. You just have to pick which you can live with.
History
npm started out managing node.js modules (that's why packages go into node_modules by default), but it works for the front-end...
support FragmentPagerAdapter holds reference to old fragments
... fragments that have been added to the fragment manager are saved automatically. Even if your app is killed, this information is restored when you relaunch your app.
Now consider that you have viewed a few pages, Fragments A, B and C. You know that these have been added to the fragment manager. Bec...
MySQL LIKE IN()?
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I like this answer - quick, simple, got all of the "options" in one line like I wanted (easy to edit). On the small result set I am targeting, no decrease in performance at all.
– Michael Wales
Jul 14 '09 at 19:04
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What's the difference between a method and a function?
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A function is a piece of code that is called by name. It can be passed data to operate on (i.e. the parameters) and can optionally return data (the return value). All data that is passed to a function is explicitly passed.
A method is a piece of code that is call...
Best way to include CSS? Why use @import?
Basically I am wondering what is the advantage / purpose of using @import to import stylesheets into an existing stylesheet versus just adding another ...
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How can I find non-ASCII characters in MySQL?
...ame WHERE columnToCheck NOT REGEXP '[A-Za-z0-9]';
That query will return all rows where columnToCheck contains any non-alphanumeric characters. If you have other characters that are acceptable, add them to the character class in the regular expression. For example, if periods, commas, and hyphens ...
How to check if a particular service is running on Ubuntu
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I don't have an Ubuntu box, but on Red Hat Linux you can see all running services by running the following command:
service --status-all
On the list the + indicates the service is running, - indicates service is not running, ? indicates the service state cannot be determined.
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