Ordered Set and GNU C++ PBDS

In this tutorial, we will be discussing a program to understand ordered set and GNU C++ PBDS.

Ordered set is a policy based structure other than those in the STL library. The ordered set keeps all the elements in a sorted order and doesn’t allow duplicate values.

Example

 Live Demo

#include <iostream> using namespace std; #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/tree_policy.hpp> using namespace __gnu_pbds; #define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update> int main(){    //declaring ordered set    ordered_set o_set;    o_set.insert(5);    o_set.insert(1);    o_set.insert(2);    cout << *(o_set.find_by_order(1))     << endl;    cout << o_set.order_of_key(4)     << endl;    cout << o_set.order_of_key(5)     << endl;    if (o_set.find(2) != o_set.end())     o_set.erase(o_set.find(2));    cout << *(o_set.find_by_order(1))     << endl;    cout << o_set.order_of_key(4)     << endl;    return 0; }

Output

2 2 2 5 1