简单来说,unordered_key非常的高效,使用值本身作为键值 Example #include<iostream>#include<unordered_set>using namespace std;intmain(){// 1. initialize a hash setunordered_set<int>hashset;// 2. insert a new keyhashset.insert(1);hashset.insert(2);hashset.insert(3);// 3. delete a keyhash...
Internally, the elements in the unordered_set are not sorted in any particular order, but organized into buckets depending on their hash values to allow for fast access to individual elements directly by their values (with a constant average time complexity on average). unordered_set containers ar...
insert,emplace,emplace_hintOnly if causes rehash eraseOnly to the element erased Notes The swap functions do not invalidate any of the iterators inside the container, but they do invalidate the iterator marking the end of the swap region. ...
size_t x = 0 ; { std::cout <<"vector: insert & sort - "; timer t ; insert( data_set, vec ) ; } { std::cout <<" vector: find - "; timer t ; x += find( searched_values, vec ) ; } { std::cout <<"\n set: insert - "; timer t ; insert( data_set, set ) ;...
But in the worst-case scenario, the unordered_map is slower than a map because the worst time complexity of all the operations in an unordered_map (O(n)) is greater than the time complexity for all the operations in a map (O(log n)). ...
Complexity Constant. Iterator validity All iterators, pointers and references remain valid, but now are referring to elements in the other container, and iterate in it. non-member overloads: operators (unordered_set) swap (unordered_set)
unordered_set::insert unordered_set::insert_range (C++23) unordered_set::emplace unordered_set::emplace_hint Lookup unordered_set::count unordered_set::find unordered_set::contains (C++20) unordered_set::equal_range Bucket interface unordered_set::begin(size_type)unordered_set::cbegin(size_type...
std::unordered_set::begin container iterator (1) iterator begin() noexcept;const_iterator begin() const noexcept; bucket iterator (2) local_iterator begin ( size_type n );const_local_iterator begin ( size_type n ) const; Return iterator to beginning ...
#include<iostream>#include<string>#include<unordered_set>usingnamespacestd;boolisPresent(string s,charch){unordered_set<char>set;for(inti=0;i<s.size();i++){set.insert(s[i]);}if(set.count(ch)==1){cout<<"char "<<ch<<" is present so it will print: ";returntrue;}cout<<"char ...
Time complexityconstant time.ExampleThe following example shows the usage of std::unordered_set::unordered_set.Live Demo #include <iostream> #include <string> #include <unordered_set> template<class T> T cmerge (T a, T b) { T t(a); t.insert(b.begin(),b.end()); return t; } ...