#include <algorithm>
#include <cassert>
#include <iterator>
#include <vector>
void discard_negative(std::vector<int>& tasks) {
    const auto end = std::remove_if(tasks.begin(), tasks.end(),
        [](int value) { return value < 0; });
    tasks.erase(end, tasks.end());
}
int main() {
    const std::vector<int> original{3, -1, 0, -2, 3};
    std::vector<int> selected;
    std::copy_if(original.begin(), original.end(), std::back_inserter(selected),
        [](int value) { return value >= 0; });
    const std::vector<int> expected{3, 0, 3};
    assert(selected == expected);
    auto modified = original;
    discard_negative(modified);
    assert(modified == expected && original[1] == -1);
    std::vector<int> empty;
    discard_negative(empty);
    assert(empty.empty());
    std::vector<int> rejected{-1, -2};
    discard_negative(rejected);
    assert(rejected.empty());
}