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Unordered Set⚓︎
This data structure is used for the case we DON'T need the key-value pairs like in the unordered_map. It is a easy way to implement presence/absence
Directory⚓︎
insert()⚓︎
Example
#include <iostream>
#include <unordered_set>
using namespace std;
//declare an unordered set globally
unordered_set Set = {2, -1};
int main()
{
//insert the element
Set.insert(1);
for (auto itr = Set.begin(); itr != Set.end(); itr++)
{
cout << (*itr) << endl;
}
}
count()⚓︎
Details
Used to check if an element is present in the container or not. The function returns 1 if the element is present in the container; otherwise, it returns 0.
Equals to return (Set.find(<element>) != Set.end());. Same performance. See find().
Example
#include <iostream>
#include <unordered_set>
using namespace std;
//declare an unordered set globally
unordered_set Set = {2, -1, 1, 2};
int main()
{
cout << "2 exsists times: " << Set.count(2) << endl;
cout << "All elements:" << endl;
for (auto itr = Set.begin(); itr != Set.end(); itr++)
{
cout << (*itr) << " " << endl;
}
}
find()⚓︎
Example
#include <iostream>
#include <unordered_set>
using namespace std;
//declare an unordered set globally
unordered_set Set = {2, -1, 1, 2};
int main()
{
//Check result using find()
cout << (Set.find(-1) != Set.end()) << endl;
//Check result using count()
cout << Set.count(-1) << endl;
}