Codility Fish

We are given in input two same sized integer vectors, the first containing fish dimensions, all of them are different, the second their direction, upstream or downstream.
The river is so narrow that fishes going in opposite direction have no choice but colliding, and the smaller one will soccumb, eaten by the other.
We want to know how many fishes will survive in the end.

I have already written a couple of posts on this problem. One where I show a naive, with N squared time complexity, solution, and another one where I implement a linear solution.

I worked on it once again, now that we can use C++11 to solve codility problems. However I didn't get anything different from that time. I just wrote the test cases in a more clean way, using the new syntax that allows creating a vector from an initialization list.

Nothing new to say about it, I am sorry to say.