Sort value and return its index using C++

template <typename T>
vector<T> sortIndexes(const vector<T> &v, bool ascend) {
    // initialize original index locations
    IntList idx(v.size());
    iota(idx.begin(), idx.end(), 0);
    // sort indexes based on comparing values in v
    sort(idx.begin(), idx.end(), [&v, ascend](size_t i1, size_t i2) {return  ascend ? v[i1] < v[i2] : v[i1] > v[i2];});
    return idx;
}