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What's the simplest way to test whether a number is a power of 2 in C++?
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so basically (n>0 && ((n & (n-1)) == 0))
– Saurabh Goyal
Jul 10 '16 at 8:06
1
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Knight's Shortest Path on Chessboard
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You have a graph here, where all available moves are connected (value=1), and unavailable moves are disconnected (value=0), the sparse matrix would be like:
(a1,b3)=1,
(a1,c2)=1,
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And the shortest path of two points in a graph can be found usin...
The difference between fork(), vfork(), exec() and clone()
...d I expected there to be a huge amount of information on this, but there really wasn't any solid comparison between the four calls.
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Making an array of integers in iOS
...rays are such a hassle for anything but trivial, one-off use that it's actually less trouble to wrap any arrays you plan on keeping around as NSArrays of NSNumber.
– Chuck
Jul 27 '10 at 1:58
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Random row selection in Pandas dataframe
... Thanks @eumiro. I also worked out that df.ix[np.random.random_integers(0, len(df), 10)] would also work.
– John
Apr 10 '13 at 10:58
7
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Sending command line arguments to npm script
... a parsing library like yargs or minimist; nodejs exposes process.argv globally, containing command line parameter values, but this is a low-level API (whitespace-separated array of strings, as provided by the operating system to the node executable).
Edit 2013.10.03: It's not currently possible...
Time complexity of Sieve of Eratosthenes algorithm
...oose upper-bound is n(1+1/2+1/3+1/4+1/5+1/6+…1/n) (sum of reciprocals of all numbers up to n), which is O(n log n): see Harmonic number. A more proper upper-bound is n(1/2 + 1/3 + 1/5 + 1/7 + …), that is sum of reciprocals of primes up to n, which is O(n log log n). (See here or here.)
The "find...
How to know/change current directory in Python shell?
...now how to change.
edit
Under Windows:
set PYTHONPATH=%PYTHONPATH%;C:\My_python_lib
(taken from http://docs.python.org/using/windows.html)
edit 2
... and even better: use virtualenv and virtualenv_wrapper, this will allow you to create a development environment where you can add module paths ...
How do you reference a capture group with regex find and replace in Visual Studio 2012, 2013, 2015,
...gular expressions' is checked, and put the following as the text to find:
_platformActions.InstallApp\((.+)\)
And the following as the text to replace it with:
this.Platform().App($1).Install()
Note: As SLaks points out in a comment below, the change in regex syntax is due to VS2012 switching to...
Array.push() if does not exist?
... it doesn't then just push the item into the array:
var newItem = "NEW_ITEM_TO_ARRAY";
var array = ["OLD_ITEM_1", "OLD_ITEM_2"];
array.indexOf(newItem) === -1 ? array.push(newItem) : console.log("This item already exists");
console.log(array)
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