stl SET.txt

//https://www.hackerrank.com/challenges/cpp-sets/problem
/*Declaration:
set<int>s; //Creates a set of integers.
Size:
int length=s.size(); //Gives the size of the set.
Insert:
s.insert(x); //Inserts an integer x into the set s.
Erasing an element:
s.erase(val); //Erases an integer val from the set s.
Finding an element:
set<int>::iterator itr=s.find(val); //Gives the iterator to the element val if it is found otherwise returns s.end() .
Ex: set<int>::iterator itr=s.find(100); //If 100 is not present then it==s.end().*/
#include<bits/stdc++.h>
using namespace std;
int main() 
{
    int t;
    cin>>t;
    set <int> s;
    while(t--)
    {
        int x,y;
        cin>>y>>x;
        if(y==1)
            s.insert(x);
        else if(y==2)
            s.erase(x);
        else
        {
            if(s.end()==s.find(x))
                cout<<"No"<<endl;
            else
                cout<<"Yes"<<endl;
        }
    }
    return 0;
}