Policy Based Data Structure

pbds.cpp

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp> 
#include <ext/pb_ds/tree_policy.hpp> 

using namespace std;
using namespace __gnu_pbds;

typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> pbds;

int main(){

  pbds A;

  //Add elements in any random order
  A.insert(11);
  A.insert(1);
  A.insert(5);
  A.insert(3);
  A.insert(7);
  A.insert(9);


  //Total contents
  cout << "1, 3, 5, 7, 9, 11" << endl;


  //K-th smallest
  int k = 3;
  cout << k << "rd smallest: " << *A.find_by_order(k-1) << endl;

  k = 5;
  cout << k << "th smallest: " << *A.find_by_order(k-1) << endl;


  //NO OF ELEMENTS < X
  int X = 9;

  cout << "No of elements less than " << X << " are " << A.order_of_key(X) << endl;

  //DELETE Elements
  cout << "Deleted 3" << endl;
  A.erase(3);

  //Total contents
  cout << "1, 5, 7, 9, 11" << endl;

  cout << "No of elements less than " << X << " are " << A.order_of_key(X) << endl;

  //NEXT BIGGER/SMALLER ELEMENT than X
  X = 8;

  cout << "Next greater element than " << X << " is " << *A.upper_bound(X) << endl;


  return 0;
}

Does this works for repeated elements too ?