Maximise count of intersections possible from the given endpoints of a line

#include <iostream>

using namespace std;

#include <ext/pb_ds/assoc_container.hpp> // Common file

#include <ext/pb_ds/tree_policy.hpp>

#include <functional> // for less

#include <iostream>

using namespace std;

using namespace __gnu_pbds;

template <class T>

using oset

    = tree<T, null_type, greater_equal<T>, rb_tree_tag,

           tree_order_statistics_node_update>;

void maximumIntersection(int EndPoints[], int N)

{

    oset<int> st;

    int ans = 0;

    map<int, int> mp;

    for (int i = 0; i < N; i++) {

        st.insert(EndPoints[i]);

        ans += st.order_of_key(EndPoints[i])

               + mp[EndPoints[i]];

        mp[EndPoints[i]]++;

    }

    if (mp.size() == 1) {

        cout << "Maximum Intersection Possible: " << ans / 2

             << "\n";

    }

    else {

        cout << "Maximum Intersection Possible: " << ans

             << "\n";

    }

}

int main()

{

    int X = 7;

    int EndPoints[] = { 4, 1, 4, 6, 7, 7, 5 };

    int Y = 5;

    int EndPoints2[] = { 2, 1, 4, 3, 5 };

    int Z = 5;

    int EndPoints3[] = { 1, 1, 1, 1, 1 };

    maximumIntersection(EndPoints, X);

    maximumIntersection(EndPoints2, Y);

    maximumIntersection(EndPoints3, Z);

}

#include <iostream>

using namespace std;

#include <ext/pb_ds/assoc_container.hpp> // Common file

#include <ext/pb_ds/tree_policy.hpp>

#include <functional> // for less

#include <iostream>

using namespace std;

using namespace __gnu_pbds;

template <class T>

using oset

    = tree<T, null_type, greater_equal<T>, rb_tree_tag,

           tree_order_statistics_node_update>;

void maximumIntersection(int EndPoints[], int N)

{

    oset<int> st;

    int ans = 0;

    map<int, int> mp;

    for (int i = 0; i < N; i++) {

        st.insert(EndPoints[i]);

        ans += st.order_of_key(EndPoints[i])

               + mp[EndPoints[i]];

        mp[EndPoints[i]]++;

    }

    if (mp.size() == 1) {

        cout << "Maximum Intersection Possible: " << ans / 2

             << "\n";

    }

    else {

        cout << "Maximum Intersection Possible: " << ans

             << "\n";

    }

}

int main()

{

    int X = 7;

    int EndPoints[] = { 4, 1, 4, 6, 7, 7, 5 };

    int Y = 5;

    int EndPoints2[] = { 2, 1, 4, 3, 5 };

    int Z = 5;

    int EndPoints3[] = { 1, 1, 1, 1, 1 };

    maximumIntersection(EndPoints, X);

    maximumIntersection(EndPoints2, Y);

    maximumIntersection(EndPoints3, Z);

}