[vector.cons]

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constexpr explicit vector(const Allocator&) noexcept;

Effects: Constructs an empty vector, using the specified allocator.

Complexity: Constant.

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constexpr explicit vector(size_type n, const Allocator& = Allocator();

Effects: Constructs a vector with n default-inserted elements using the specified allocator.

Complexity: Linear in n.

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constexpr vector(size_type n, const T& value,
                 const Allocator& = Allocator();

Preconditions: T is Cpp17CopyInsertable into vector.

Effects: Constructs a vector with n copies of value, using the specified allocator.

Complexity: Linear in n.

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template<class InputIterator>
  constexpr vector(InputIterator first, InputIterator last,
                   const Allocator& = Allocator();

Effects: Constructs a vector equal to the range [first, last), using the specified allocator.

Complexity: Makes only N calls to the copy constructor of T (where N is the distance between first and last) and no reallocations if InputIterator meets the Cpp17ForwardIterator requirements.

It makes order N calls to the copy constructor of T and order

log N reallocations if they are just input iterators .

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template<container-compatible-range<T> R>
  constexpr vector(from_range_t, R&& rg, const Allocator& = Allocator();

Effects: Constructs a vector object with the elements of the range rg, using the specified allocator.

Complexity: Initializes exactly N elements from the results of dereferencing successive iterators of rg, where N is ranges::distance(rg).

Performs no reallocations if:

(13.1)
R models ranges::approximately_sized_range, and ranges::distance(rg) <= ranges::reserve_hint(rg) is true, or
(13.2)
R models ranges::forward_range and R does not model ranges::approximately_sized_range.

Otherwise, performs order

log N reallocations and order N calls to the copy or move constructor of T .

23 Containers library [containers]

23.3 Sequence containers [sequences]

23.3.13 Class template vector [vector]

23.3.13.2 Constructors [vector.cons]