Fastest way to sort a list of number and their index

Question

I have a question that could seem very basic, but it is in a context where \"every CPU tick counts\" (this is a part of a larger algorithm that will be used on supercomputers).<

Answer 1

Use std::vector and std::sort. That should provided the fastest sort method. To Find the original index create a struct.

struct A {
    int num;
    int index;
}

Then make your own compare Predicate for sort that compares the num in the struct.

struct Predicate {
    bool operator()(const A first, const A second) {
        return first.num < second.num;
    }
}

std::sort(vec.begin(), vec.end(), Predicate())