Question

I have recently read an article about fast sqrt calculation. Therefore, I have decided to ask SO community and its experts to help me find out, which STL algorithms or mathematical calculations can be implemented faster with programming hacks?

It would be great if you can give examples or links.

Thanks in advance.

Answer 1

Several of the algorithms in <algorithm> can be optimized for vector<bool>::[const_]iterator. These include:

find
count
fill
fill_n
copy
copy_backward
move // C++0x
move_backward  // C++0x
swap_ranges
rotate
equal

I’ve probably missed some. But all of the above algorithms can be optimized to work on many bits at a time instead of just one bit at a time (as would a naive implementation).

This is an optimization that I suspect is sorely missing from most STL implementations. It is not missing from this one:

http://libcxx.llvm.org/