Method resize

include/util/packed_vector.hpp:493–498

    std::size_t size() const { return num_elements; }

    void resize(std::size_t elements)
    {
        num_elements = elements;
        auto num_blocks = (elements + BLOCK_ELEMENTS - 1) / BLOCK_ELEMENTS;
        vec.resize(num_blocks * BLOCK_WORDS + 1);
    }

    std::size_t capacity() const { return (vec.capacity() / BLOCK_WORDS) * BLOCK_ELEMENTS; }