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What are the differences between NP, NP-Complete and NP-Hard?
... the technical definitions require quite some time to understand. First of all, let's remember a preliminary needed concept to understand those definitions.
Decision problem: A problem with a yes or no answer.
Now, let us define those complexity classes.
P
P is a complexity class that repres...
How to write iOS app purely in C
...d in remain the same whether or not
// you are using VA_ARGS. This is actually the basis of the objective-c
// runtime (objc_msgSend), so we are probably fine here, this would be
// the last thing I would expect to break.
extern int UIApplicationMain(int, ...);
// Entry point of the application....
Escaping regex string
...this:
4.2.3 re Module Contents
escape(string)
Return string with all non-alphanumerics backslashed; this is useful if you want to match an arbitrary literal string that may have regular expression metacharacters in it.
A simplistic example, search any occurence of the provided string opt...
Static class initializer in PHP
I have an helper class with some static functions. All the functions in the class require a ‘heavy’ initialization function to run once (as if it were a constructor).
...
Download the Android SDK components for offline install
Is it possible to download the Android SDK components for offline install without using the SDK Manager?
The problem is I am behind a firewall which I have no control over and both sites download URLs seem to be blocked (throws a connection refused exception)
...
How do I get the path to the current script with Node.js?
...
So basically you can do this:
fs.readFile(path.resolve(__dirname, 'settings.json'), 'UTF-8', callback);
Use resolve() instead of concatenating with '/' or '\' else you will run into cross-platform issues.
Note: __dirname is the l...
Calculate difference in keys contained in two Python dictionaries
...s:
diff = set(dictb.keys()) - set(dicta.keys())
Here is a class to find all the possibilities: what was added, what was removed, which key-value pairs are the same, and which key-value pairs are changed.
class DictDiffer(object):
"""
Calculate the difference between two dictionaries as:
...
How do you get the list of targets in a makefile?
...ed rake a bit (a Ruby make program), and it has an option to get a list of all the available targets, eg
20 Answers
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ViewPager and fragments — what's the right way to store fragment's state?
...agment will be placed. FragmentPagerAdapter.getItem(int position) is only called when a fragment for that position does not exist. After rotating, Android will notice that it already created/saved a fragment for this particular position and so it simply tries to reconnect with it with FragmentManage...
Find MongoDB records where array field is not empty
All of my records have a field called "pictures". This field is an array of strings.
11 Answers
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