Unordered Set

#include <unordered_set>
  
unordered_set<int> s;                       // create an unordered_set of integers
unordered_set<int> s({4, 3, 9, 2, 0, 6});   // create an unordered_set with few initial elements
     
cout << s.size() << endl;                   // number of elements in unordered_set
s.insert(123);                              // add element to unordered_set
s.erase(444);                               // erase an element from the unordered_set
s.clear();                                  // remove all the elements from the unordered_set
        

// search for an element
if (s.find(444) != s.end()) {
    // It means 444 exists in the set
} 

// iterate over all elements
for(unordered_set<int>::iterator it = s.begin(); it != s.end(); it++) {
    cout << *it << endl;
}