std::partial_sort_copy

#include <algorithm>
#include <vector>
#include <functional>
#include <iostream>
 
int main()
{
    std::vector<int> v0{4, 2, 5, 1, 3};
    std::vector<int> v1{10, 11, 12};
    std::vector<int> v2{10, 11, 12, 13, 14, 15, 16};
    std::vector<int>::iterator it;
 
    it = std::partial_sort_copy(v0.begin(), v0.end(), v1.begin(), v1.end());
 
    std::cout << "Writing to the smaller vector in ascending order gives: ";
    for (int a : v1) {
        std::cout << a << " ";
    }
    std::cout << '\n';
    if(it == v1.end())
        std::cout << "The return value is the end iterator\n";
 
    it = std::partial_sort_copy(v0.begin(), v0.end(), v2.begin(), v2.end(), 
                                std::greater<int>());
 
    std::cout << "Writing to the larger vector in descending order gives: ";
    for (int a : v2) {
        std::cout << a << " ";
    }
    std::cout << '\n' << "The return value is the iterator to " << *it << '\n';
}