constexpr size_type capacity() const noexcept;
constexpr void reserve(size_type n);
constexpr void shrink_to_fit();
constexpr void swap(vector& x)
noexcept(allocator_traits<Allocator>::propagate_on_container_swap::value ||
allocator_traits<Allocator>::is_always_equal::value);
constexpr void resize(size_type sz);
constexpr void resize(size_type sz, const T& c);