std::merge

Code

namespace STL {
    vector<int> merge(vector<int> a, vector<int> b) {
        vector<int> c(a.size() + b.size());
        auto x = a.begin(), y = b.begin(), z = c.begin();
        while (z != c.end()) {
            if (x == a.end()) { *z++ = *y++; continue; }
            if (y == b.end()) { *z++ = *x++; continue; }
            *z++ = (*x > *y) ? *y++ : *x++;
        }
        return c;
    }
}