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Fast way of counting non-zero bits in positive integer
...1") is the fastest I could find in pure Python.
I tried adapting Óscar's and Adam's solutions to process the integer in 64-bit and 32-bit chunks, respectively. Both were at least ten times slower than bin(n).count("1") (the 32-bit version took about half again as much time).
On the other hand, gm...
Wrapping null-returning method in Java with Option in Scala?
...ause Try is not about nullability checking but just a way to functionally handle exceptions.
Using Try to catch an exception and converting that to an Option for convenience will only show None in case an exception happens.
scala> Try(1/0).toOption
res11: Option[Int] = None
You want to preser...
What is the difference between t.belongs_to and t.references in rails?
What is the difference between t.references and t.belongs_to ?
Why are we having those two different words? It seems to me they do the same thing?
Tried some Google search, but find no explanation.
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Counting the occurrences / frequency of array elements
In Javascript, I'm trying to take an initial array of number values and count the elements inside it. Ideally, the result would be two new arrays, the first specifying each unique element, and the second containing the number of times each element occurs. However, I'm open to suggestions on the form...
How do I put my website's logo to be the icon image in browser tabs?
...
That image is called 'favicon' and it's a small square shaped .ico file, which is the standard file type for favicons. You could use .png or .gif too, but you should follow the standard for better compatibility.
To set one for your website you should:
M...
What does JVM flag CMSClassUnloadingEnabled actually do?
...//blogs.oracle.com/poonam/about-g1-garbage-collector,-permanent-generation-and-metaspace Kudos go to mt.uulu
For Java 5-7:
The standard Oracle/Sun VM look on the world is: Classes are forever. So once loaded, they stay in memory even if no one cares anymore. This usually is no problem since you do...
What is the Ruby (spaceship) operator?
...en return -1
if a = b then return 0
if a > b then return 1
if a and b are not comparable then return nil
It's useful for sorting an array.
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How to check if a file exists in Documents folder?
... if it was a main application you'll have access to the entire file system and you'll use the shared Documents directory. If you install it via iTunes or XCode you'll be using your applications' personal directory. It's nice to store files in your local directory for backup purposes.
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Bash/sh - difference between && and ;
I normally use ; to combine more than one command in a line, but some people prefer && . Is there any difference? For example, cd ~; cd - and cd ~ && cd - seems to make the same thing. What version is more portable, e.g. will be supported by a bash-subset like Android's shell ...
Create Directory When Writing To File In Node.js
I've been tinkering with Node.js and found a little problem. I've got a script which resides in a directory called data . I want the script to write some data to a file in a subdirectory within the data subdirectory. However I am getting the following error:
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