[reinhardt]

Using a library for computing the permutations I guess? I haven't touched C++ for years but I'd be surprised if the 44 lines include a permutations implementation.

[dzorz]

next_permutation is in standard library (header algorithm).

[makmanalp]

For the curious, STL <algorithm> is one of those things that you wish you knew ages ago. Usually my code is much cleaner after I run through it and replace relevant parts of it with STL stuff.

http://www.cplusplus.com/reference/algorithm/