yep, but if you've already mastered all the logic behind the simple permutation, sometimes using a stl function would come with less TC compared to coding on your own. This solution provides some insights with me, though I still deem it cheating XD

I meant O(n log(n)). And considering the number of people complaining about timeouts, they wrote a O(n^2) one.

You didn't write a O(log n) solution.

That's a cheating!)

How it work?

what is going on its just a sum mate

Aah yes, sort. I tried using next_permutation, but I don't think it works with an unsorted string. Nice one!

This is the Enterprise way.

Darn, I should've looked for a library function when Knuth said that people often want all the permutations :D

*yawn... no recursion

:D

thank you for pointing this out

Not sure if possible, but you could perhaps #define while cheat_detection(); while
It doesn't matter that that turns it into two statements, just as long as the cheat_detection() is called you will (silently) fail the test. Be sure to VERY CLEARLY state that 'while' is not allowed to be used ;).

If people know you do this they can work around it, of course.

How the hell do you write an O(log n) algorithm for a function with n integer inputs...

I am not happy. I spent a lot of time on writing a solution that is O(log(n)) because the description said it was necessary to write an efficient algorithm (and it should be); then I find out that everyone else wrote a simplistic O(n) "solution" and got away with it. :/ That is not right.