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How can I pair socks from a pile efficiently?

...ent than a modern CPU, this question makes no practical sense. Humans can win over CPU algorithms using the fact that "finding a matching pair" can be one operation for a set that isn't too big. My algorithm: spread_all_socks_on_flat_surface(); while (socks_left_on_a_surface()) { // Thanks t...
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What are the differences between Autotools, Cmake and Scons?

... a painful experience to get an Autotools setup to build usable code for a Windows system. (While I've little use for Windows, it is a serious concern if you're developing purportedly cross-platform code.) When it breaks, you're going to spend HOURS chasing your tail trying to sort out the things t...
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How many GCC optimization levels are there?

... further optimizations designed to reduce code size. -Os disables the following optimization flags: -falign-functions -falign-jumps -falign-loops -falign-labels -freorder-blocks -freorder-blocks-and-partition -fprefetch-loop-arrays -ftree-vect-loop-version) There may also be platform specific opti...
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Why do we use __init__ in Python classes?

... class Brazilian(Humans) def do_your_special_thing win_every_football_world_cup() class Germans(Humans) def drink(beverage): if favorite_drink != beverage: print "I need more beer" else: print "Lecker!" class HighSchoolStudent(Americ...
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Why do pthreads’ condition variable functions require a mutex?

...ed before you do a wait. The wait will "atomically" unlock the mutex, allowing others access to the condition variable (for signalling). Then when the condition variable is signalled or broadcast to, one or more of the threads on the waiting list will be woken up and the mutex will be magically loc...
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How is Node.js inherently faster when it still relies on Threads internally?

I just watched the following video: Introduction to Node.js and still don't understand how you get the speed benefits. 6 ...
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Detect if Visual C++ Redistributable for Visual Studio 2012 is installed

...e of these reg locations may be OS-dependent. I collected this info from a Windows 10 x64 box. I'm just going to go ahead and dump all of these redist versions and the reg keys I search for to detect installation.: Visual C++ 2005 Microsoft Visual C++ 2005 Redistributable (x64) Registry Key: HKL...
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How are virtual functions and vtable implemented?

...ect(*(void **)x,8,PROT_READ|PROT_WRITE|PROT_EXEC); // Or VirtualProtect on win32; this part's very OS-specific (*(int (***)(A *)x)[0] = f3; // Now C::f1() returns 0 (remember we made x into a C above) // so x->f1() and z->f1() both return 0 The latter is rather likely to make virus-checkers ...
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What are the effects of exceptions on performance in Java?

... this already happens in the try statement. The throw statement needs to unwind the stack and restore the values of all registers (and possible other values in the VM). So try and throw are equally slow, and that is pretty slow, however if no exception is thrown, exiting the try block takes no time ...
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Optimise PostgreSQL for fast testing

...s as fsync=off without the giant data corruption risk. You do have a small window of loss of recent data if you enable async commit - but that's it. If you have the option of slightly altering the DDL, you can also use UNLOGGED tables in Pg 9.1+ to completely avoid WAL logging and gain a real speed...