Problem : https://www.hackerrank.com/challenges/cpp-sets/problem
Solution :
#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <set>
#include <algorithm>
using namespace std;
int main() {
/* Enter your code here. Read input from STDIN. Print output to STDOUT */
int q;
cin>>q;
set<int>s;
while(q--) {
int y , x;
cin>>y>>x;
if( y == 1){
s.insert(x);
}else if ( y == 2){
s.erase(x);
}else if ( y == 3){
set<int>::iterator itr = s.find(x);
if(itr == s.end()){
cout<<"No\n";
}else{
cout<<"Yes\n";
}
}
}
return 0;
}