This header is part of the containers library.
Includes |
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(C++20) | Three-way comparison operator support |
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(C++11) | std::initializer_list class template |
Classes |
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(C++11) | collection of unique keys, hashed by keys (class template) |
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(C++11) | collection of keys, hashed by keys (class template) |
Functions |
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(removed in C++20) | compares the values in the unordered_set (function template) |
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(C++11) | specializes the std::swap algorithm (function template) |
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(C++20) | erases all elements satisfying specific criteria (function template) |
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(removed in C++20) | compares the values in the unordered_multiset (function template) |
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(C++11) | specializes the std::swap algorithm (function template) |
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(C++20) | erases all elements satisfying specific criteria (function template) |
Range access |
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(C++11)(C++14) | returns an iterator to the beginning of a container or array (function template) |
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(C++11)(C++14) | returns an iterator to the end of a container or array (function template) |
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(C++14) | returns a reverse iterator to the beginning of a container or array (function template) |
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(C++14) | returns a reverse end iterator for a container or array (function template) |
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(C++17)(C++20) | returns the size of a container or array (function template) |
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(C++17) | checks whether the container is empty (function template) |
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(C++17) | obtains the pointer to the underlying array (function template) |
#include <compare>
#include <initializer_list>
namespace std {
// class template unordered_set
template<class Key,
class Hash = hash<Key>,
class Pred = equal_to<Key>,
class Alloc = allocator<Key>>
class unordered_set;
// class template unordered_multiset
template<class Key,
class Hash = hash<Key>,
class Pred = equal_to<Key>,
class Alloc = allocator<Key>>
class unordered_multiset;
template<class Key, class Hash, class Pred, class Alloc>
bool operator==(const unordered_set<Key, Hash, Pred, Alloc>& a,
const unordered_set<Key, Hash, Pred, Alloc>& b);
template<class Key, class Hash, class Pred, class Alloc>
bool operator==(const unordered_multiset<Key, Hash, Pred, Alloc>& a,
const unordered_multiset<Key, Hash, Pred, Alloc>& b);
template<class Key, class Hash, class Pred, class Alloc>
void swap(unordered_set<Key, Hash, Pred, Alloc>& x,
unordered_set<Key, Hash, Pred, Alloc>& y)
noexcept(noexcept(x.swap(y)));
template<class Key, class Hash, class Pred, class Alloc>
void swap(unordered_multiset<Key, Hash, Pred, Alloc>& x,
unordered_multiset<Key, Hash, Pred, Alloc>& y)
noexcept(noexcept(x.swap(y)));
// erasure for unordered_set
template<class K, class H, class P, class A, class Predicate>
typename unordered_set<K, H, P, A>::size_type
erase_if(unordered_set<K, H, P, A>& c, Predicate pred);
// erasure for unordered_multiset
template<class K, class H, class P, class A, class Predicate>
typename unordered_multiset<K, H, P, A>::size_type
erase_if(unordered_multiset<K, H, P, A>& c, Predicate pred);
namespace pmr {
template<class Key,
class Hash = hash<Key>,
class Pred = equal_to<Key>>
using unordered_set = std::unordered_set<Key, Hash, Pred,
polymorphic_allocator<Key>>;
template<class Key,
class Hash = hash<Key>,
class Pred = equal_to<Key>>
using unordered_multiset = std::unordered_multiset<Key, Hash, Pred,
polymorphic_allocator<Key>>;
}
}std::unordered_set
namespace std {
template<class Key,
class Hash = hash<Key>,
class Pred = equal_to<Key>,
class Allocator = allocator<Key>>
class unordered_set {
public:
// types
using key_type = Key;
using value_type = Key;
using hasher = Hash;
using key_equal = Pred;
using allocator_type = Allocator;
using pointer = typename allocator_traits<Allocator>::pointer;
using const_pointer = typename allocator_traits<Allocator>::const_pointer;
using reference = value_type&;
using const_reference = const value_type&;
using size_type = /* implementation-defined */;
using difference_type = /* implementation-defined */;
using iterator = /* implementation-defined */;
using const_iterator = /* implementation-defined */;
using local_iterator = /* implementation-defined */;
using const_local_iterator = /* implementation-defined */;
using node_type = /* unspecified */;
using insert_return_type = __insert_return_type<iterator, node_type>;
// construct/copy/destroy
unordered_set();
explicit unordered_set(size_type n,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
template<class InputIt>
unordered_set(InputIt f, InputIt l,
size_type n = /* see description */,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
template<__container_compatible_range<value_type> R>
unordered_set(from_range_t, R&& rg,
size_type n = /* see description */,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
unordered_set(const unordered_set&);
unordered_set(unordered_set&&);
explicit unordered_set(const Allocator&);
unordered_set(const unordered_set&, const type_identity_t<Allocator>&);
unordered_set(unordered_set&&, const type_identity_t<Allocator>&);
unordered_set(initializer_list<value_type> il,
size_type n = /* see description */,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
unordered_set(size_type n, const allocator_type& a)
: unordered_set(n, hasher(), key_equal(), a) { }
unordered_set(size_type n, const hasher& hf, const allocator_type& a)
: unordered_set(n, hf, key_equal(), a) { }
template<class InputIt>
unordered_set(InputIt f, InputIt l, size_type n, const allocator_type& a)
: unordered_set(f, l, n, hasher(), key_equal(), a) { }
template<class InputIt>
unordered_set(InputIt f, InputIt l, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_set(f, l, n, hf, key_equal(), a) { }
unordered_set(initializer_list<value_type> il, size_type n, const allocator_type& a)
: unordered_set(il, n, hasher(), key_equal(), a) { }
template<__container_compatible_range<value_type> R>
unordered_set(from_range_t, R&& rg, size_type n, const allocator_type& a)
: unordered_set(from_range, std::forward<R>(rg), n, hasher(), key_equal(), a) { }
template<__container_compatible_range<value_type> R>
unordered_set(from_range_t, R&& rg, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_set(from_range, std::forward<R>(rg), n, hf, key_equal(), a) { }
unordered_set(initializer_list<value_type> il, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_set(il, n, hf, key_equal(), a) { }
~unordered_set();
unordered_set& operator=(const unordered_set&);
unordered_set& operator=(unordered_set&&)
noexcept(allocator_traits<Allocator>::is_always_equal::value &&
is_nothrow_move_assignable_v<Hash> &&
is_nothrow_move_assignable_v<Pred>);
unordered_set& operator=(initializer_list<value_type>);
allocator_type get_allocator() const noexcept;
// iterators
iterator begin() noexcept;
const_iterator begin() const noexcept;
iterator end() noexcept;
const_iterator end() const noexcept;
const_iterator cbegin() const noexcept;
const_iterator cend() const noexcept;
// capacity
[[nodiscard]] bool empty() const noexcept;
size_type size() const noexcept;
size_type max_size() const noexcept;
// modifiers
template<class... Args> pair<iterator, bool> emplace(Args&&... args);
template<class... Args> iterator emplace_hint(const_iterator position,
Args&&... args);
pair<iterator, bool> insert(const value_type& obj);
pair<iterator, bool> insert(value_type&& obj);
iterator insert(const_iterator hint, const value_type& obj);
iterator insert(const_iterator hint, value_type&& obj);
template<class InputIt> void insert(InputIt first, InputIt last);
template<__container_compatible_range<value_type> R>
void insert_range(R&& rg);
void insert(initializer_list<value_type>);
node_type extract(const_iterator position);
node_type extract(const key_type& x);
template<class K> node_type extract(K&& x);
insert_return_type insert(node_type&& nh);
iterator insert(const_iterator hint, node_type&& nh);
iterator erase(iterator position)
requires (!same_as<iterator, const_iterator>);
iterator erase(const_iterator position);
size_type erase(const key_type& k);
template<class K> size_type erase(K&& x);
iterator erase(const_iterator first, const_iterator last);
void swap(unordered_set&)
noexcept(allocator_traits<Allocator>::is_always_equal::value &&
is_nothrow_swappable_v<Hash> &&
is_nothrow_swappable_v<Pred>);
void clear() noexcept;
template<class H2, class P2>
void merge(unordered_set<Key, H2, P2, Allocator>& source);
template<class H2, class P2>
void merge(unordered_set<Key, H2, P2, Allocator>&& source);
template<class H2, class P2>
void merge(unordered_multiset<Key, H2, P2, Allocator>& source);
template<class H2, class P2>
void merge(unordered_multiset<Key, H2, P2, Allocator>&& source);
// observers
hasher hash_function() const;
key_equal key_eq() const;
// set operations
iterator find(const key_type& k);
const_iterator find(const key_type& k) const;
template<class K>
iterator find(const K& k);
template<class K>
const_iterator find(const K& k) const;
size_type count(const key_type& k) const;
template<class K>
size_type count(const K& k) const;
bool contains(const key_type& k) const;
template<class K>
bool contains(const K& k) const;
pair<iterator, iterator> equal_range(const key_type& k);
pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
template<class K>
pair<iterator, iterator> equal_range(const K& k);
template<class K>
pair<const_iterator, const_iterator> equal_range(const K& k) const;
// bucket interface
size_type bucket_count() const noexcept;
size_type max_bucket_count() const noexcept;
size_type bucket_size(size_type n) const;
size_type bucket(const key_type& k) const;
local_iterator begin(size_type n);
const_local_iterator begin(size_type n) const;
local_iterator end(size_type n);
const_local_iterator end(size_type n) const;
const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;
// hash policy
float load_factor() const noexcept;
float max_load_factor() const noexcept;
void max_load_factor(float z);
void rehash(size_type n);
void reserve(size_type n);
};
template<class InputIt,
class Hash = hash<__iter_value_type<InputIt>>,
class Pred = equal_to<__iter_value_type<InputIt>>,
class Allocator = allocator<__iter_value_type<InputIt>>>
unordered_set(InputIt, InputIt,
typename /* see description */::size_type = /* see description */,
Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-> unordered_set<__iter_value_type<InputIt>,
Hash, Pred, Allocator>;
template<ranges::input_range R,
class Hash = hash<ranges::range_value_t<R>>,
class Pred = equal_to<ranges::range_value_t<R>>,
class Allocator = allocator<ranges::range_value_t<R>>>
unordered_set(from_range_t, R&&,
typename /* see description */::size_type = /* see description */,
Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-> unordered_set<ranges::range_value_t<R>, Hash, Pred, Allocator>;
template<class T, class Hash = hash<T>,
class Pred = equal_to<T>, class Allocator = allocator<T>>
unordered_set(initializer_list<T>,
typename /* see description */::size_type = /* see description */,
Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-> unordered_set<T, Hash, Pred, Allocator>;
template<class InputIt, class Allocator>
unordered_set(InputIt, InputIt, typename /* see description */::size_type, Allocator)
-> unordered_set<__iter_value_type<InputIt>,
hash<__iter_value_type<InputIt>>,
equal_to<__iter_value_type<InputIt>>,
Allocator>;
template<class InputIt, class Hash, class Allocator>
unordered_set(InputIt, InputIt, typename /* see description */::size_type,
Hash, Allocator)
-> unordered_set<__iter_value_type<InputIt>, Hash,
equal_to<__iter_value_type<InputIt>>,
Allocator>;
template<ranges::input_range R, class Allocator>
unordered_set(from_range_t, R&&, typename /* see description */::size_type, Allocator)
-> unordered_set<ranges::range_value_t<R>, hash<ranges::range_value_t<R>>,
equal_to<ranges::range_value_t<R>>, Allocator>;
template<ranges::input_range R, class Allocator>
unordered_set(from_range_t, R&&, Allocator)
-> unordered_set<ranges::range_value_t<R>, hash<ranges::range_value_t<R>>,
equal_to<ranges::range_value_t<R>>, Allocator>;
template<ranges::input_range R, class Hash, class Allocator>
unordered_set(from_range_t, R&&,
typename /* see description */::size_type, Hash, Allocator)
-> unordered_set<ranges::range_value_t<R>, Hash,
equal_to<ranges::range_value_t<R>>, Allocator>;
template<class T, class Allocator>
unordered_set(initializer_list<T>, typename /* see description */::size_type,
Allocator)
-> unordered_set<T, hash<T>, equal_to<T>, Allocator>;
template<class T, class Hash, class Allocator>
unordered_set(initializer_list<T>, typename /* see description */::size_type, Hash,
Allocator)
-> unordered_set<T, Hash, equal_to<T>, Allocator>;
}std::unordered_multiset
namespace std {
template<class Key,
class Hash = hash<Key>,
class Pred = equal_to<Key>,
class Allocator = allocator<Key>>
class unordered_multiset {
public:
// types
using key_type = Key;
using value_type = Key;
using hasher = Hash;
using key_equal = Pred;
using allocator_type = Allocator;
using pointer = typename allocator_traits<Allocator>::pointer;
using const_pointer = typename allocator_traits<Allocator>::const_pointer;
using reference = value_type&;
using const_reference = const value_type&;
using size_type = /* implementation-defined */;
using difference_type = /* implementation-defined */;
using iterator = /* implementation-defined */;
using const_iterator = /* implementation-defined */;
using local_iterator = /* implementation-defined */;
using const_local_iterator = /* implementation-defined */;
using node_type = /* unspecified */;
// construct/copy/destroy
unordered_multiset();
explicit unordered_multiset(size_type n,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
template<class InputIt>
unordered_multiset(InputIt f, InputIt l,
size_type n = /* see description */,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
template<__container_compatible_range<value_type> R>
unordered_multiset(from_range_t, R&& rg,
size_type n = /* see description */,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
unordered_multiset(const unordered_multiset&);
unordered_multiset(unordered_multiset&&);
explicit unordered_multiset(const Allocator&);
unordered_multiset(const unordered_multiset&, const type_identity_t<Allocator>&);
unordered_multiset(unordered_multiset&&, const type_identity_t<Allocator>&);
unordered_multiset(initializer_list<value_type> il,
size_type n = /* see description */,
const hasher& hf = hasher(),
const key_equal& eql = key_equal(),
const allocator_type& a = allocator_type());
unordered_multiset(size_type n, const allocator_type& a)
: unordered_multiset(n, hasher(), key_equal(), a) { }
unordered_multiset(size_type n, const hasher& hf, const allocator_type& a)
: unordered_multiset(n, hf, key_equal(), a) { }
template<class InputIt>
unordered_multiset(InputIt f, InputIt l, size_type n, const allocator_type& a)
: unordered_multiset(f, l, n, hasher(), key_equal(), a) { }
template<class InputIt>
unordered_multiset(InputIt f, InputIt l, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_multiset(f, l, n, hf, key_equal(), a) { }
template<__container_compatible_range<value_type> R>
unordered_multiset(from_range_t, R&& rg, size_type n, const allocator_type& a)
: unordered_multiset(from_range, std::forward<R>(rg),
n, hasher(), key_equal(), a) { }
template<__container_compatible_range<value_type> R>
unordered_multiset(from_range_t, R&& rg, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_multiset(from_range, std::forward<R>(rg), n, hf, key_equal(), a) { }
unordered_multiset(initializer_list<value_type> il, size_type n,
const allocator_type& a)
: unordered_multiset(il, n, hasher(), key_equal(), a) { }
unordered_multiset(initializer_list<value_type> il, size_type n, const hasher& hf,
const allocator_type& a)
: unordered_multiset(il, n, hf, key_equal(), a) { }
~unordered_multiset();
unordered_multiset& operator=(const unordered_multiset&);
unordered_multiset& operator=(unordered_multiset&&)
noexcept(allocator_traits<Allocator>::is_always_equal::value &&
is_nothrow_move_assignable_v<Hash> &&
is_nothrow_move_assignable_v<Pred>);
unordered_multiset& operator=(initializer_list<value_type>);
allocator_type get_allocator() const noexcept;
// iterators
iterator begin() noexcept;
const_iterator begin() const noexcept;
iterator end() noexcept;
const_iterator end() const noexcept;
const_iterator cbegin() const noexcept;
const_iterator cend() const noexcept;
// capacity
[[nodiscard]] bool empty() const noexcept;
size_type size() const noexcept;
size_type max_size() const noexcept;
// modifiers
template<class... Args> iterator emplace(Args&&... args);
template<class... Args> iterator emplace_hint(const_iterator position,
Args&&... args);
iterator insert(const value_type& obj);
iterator insert(value_type&& obj);
iterator insert(const_iterator hint, const value_type& obj);
iterator insert(const_iterator hint, value_type&& obj);
template<class InputIt> void insert(InputIt first, InputIt last);
template<__container_compatible_range<value_type> R>
void insert_range(R&& rg);
void insert(initializer_list<value_type>);
node_type extract(const_iterator position);
node_type extract(const key_type& x);
template<class K> node_type extract(K&& x);
iterator insert(node_type&& nh);
iterator insert(const_iterator hint, node_type&& nh);
iterator erase(iterator position)
requires (!same_as<iterator, const_iterator>);
iterator erase(const_iterator position);
size_type erase(const key_type& k);
template<class K> size_type erase(K&& x);
iterator erase(const_iterator first, const_iterator last);
void swap(unordered_multiset&)
noexcept(allocator_traits<Allocator>::is_always_equal::value &&
is_nothrow_swappable_v<Hash> &&
is_nothrow_swappable_v<Pred>);
void clear() noexcept;
template<class H2, class P2>
void merge(unordered_multiset<Key, H2, P2, Allocator>& source);
template<class H2, class P2>
void merge(unordered_multiset<Key, H2, P2, Allocator>&& source);
template<class H2, class P2>
void merge(unordered_set<Key, H2, P2, Allocator>& source);
template<class H2, class P2>
void merge(unordered_set<Key, H2, P2, Allocator>&& source);
// observers
hasher hash_function() const;
key_equal key_eq() const;
// set operations
iterator find(const key_type& k);
const_iterator find(const key_type& k) const;
template<class K>
iterator find(const K& k);
template<class K>
const_iterator find(const K& k) const;
size_type count(const key_type& k) const;
template<class K>
size_type count(const K& k) const;
bool contains(const key_type& k) const;
template<class K>
bool contains(const K& k) const;
pair<iterator, iterator> equal_range(const key_type& k);
pair<const_iterator, const_iterator> equal_range(const key_type& k) const;
template<class K>
pair<iterator, iterator> equal_range(const K& k);
template<class K>
pair<const_iterator, const_iterator> equal_range(const K& k) const;
// bucket interface
size_type bucket_count() const noexcept;
size_type max_bucket_count() const noexcept;
size_type bucket_size(size_type n) const;
size_type bucket(const key_type& k) const;
local_iterator begin(size_type n);
const_local_iterator begin(size_type n) const;
local_iterator end(size_type n);
const_local_iterator end(size_type n) const;
const_local_iterator cbegin(size_type n) const;
const_local_iterator cend(size_type n) const;
// hash policy
float load_factor() const noexcept;
float max_load_factor() const noexcept;
void max_load_factor(float z);
void rehash(size_type n);
void reserve(size_type n);
};
template<class InputIt,
class Hash = hash<__iter_value_type<InputIt>>,
class Pred = equal_to<__iter_value_type<InputIt>>,
class Allocator = allocator<__iter_value_type<InputIt>>>
unordered_multiset(InputIt, InputIt,
/* see description */::size_type = /* see description */,
Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-> unordered_multiset<__iter_value_type<InputIt>,
Hash, Pred, Allocator>;
template<ranges::input_range R,
class Hash = hash<ranges::range_value_t<R>>,
class Pred = equal_to<ranges::range_value_t<R>>,
class Allocator = allocator<ranges::range_value_t<R>>>
unordered_multiset(from_range_t, R&&,
typename /* see description */::size_type = /* see description */,
Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-> unordered_multiset<ranges::range_value_t<R>, Hash, Pred, Allocator>;
template<class T, class Hash = hash<T>,
class Pred = equal_to<T>, class Allocator = allocator<T>>
unordered_multiset(initializer_list<T>,
typename /* see description */::size_type = /* see description */,
Hash = Hash(), Pred = Pred(), Allocator = Allocator())
-> unordered_multiset<T, Hash, Pred, Allocator>;
template<class InputIt, class Allocator>
unordered_multiset(InputIt, InputIt,
typename /* see description */::size_type, Allocator)
-> unordered_multiset<__iter_value_type<InputIt>,
hash<__iter_value_type<InputIt>>,
equal_to<__iter_value_type<InputIt>>,
Allocator>;
template<class InputIt, class Hash, class Allocator>
unordered_multiset(InputIt, InputIt, typename /* see description */::size_type,
Hash, Allocator)
-> unordered_multiset<__iter_value_type<InputIt>, Hash,
equal_to<__iter_value_type<InputIt>>,
Allocator>;
template<ranges::input_range R, class Allocator>
unordered_multiset(from_range_t, R&&, typename /* see description */::size_type,
Allocator)
-> unordered_multiset<ranges::range_value_t<R>, hash<ranges::range_value_t<R>>,
equal_to<ranges::range_value_t<R>>, Allocator>;
template<ranges::input_range R, class Allocator>
unordered_multiset(from_range_t, R&&, Allocator)
-> unordered_multiset<ranges::range_value_t<R>, hash<ranges::range_value_t<R>>,
equal_to<ranges::range_value_t<R>>, Allocator>;
template<ranges::input_range R, class Hash, class Allocator>
unordered_multiset(from_range_t, R&&, typename /* see description */::size_type, Hash,
Allocator)
-> unordered_multiset<ranges::range_value_t<R>, Hash,
equal_to<ranges::range_value_t<R>>,
Allocator>;
template<class T, class Allocator>
unordered_multiset(initializer_list<T>, typename /* see description */::size_type,
Allocator)
-> unordered_multiset<T, hash<T>, equal_to<T>, Allocator>;
template<class T, class Hash, class Allocator>
unordered_multiset(initializer_list<T>, typename /* see description */::size_type,
Hash, Allocator)
-> unordered_multiset<T, Hash, equal_to<T>, Allocator>;
}
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