Interval Partitioning Problem

/// Reference : https://algorithmsandme.com/interval-partitioning-problem/

/// Reference : https://bit.ly/37SyI7L

/// Reference : https://www.youtube.com/watch?v=i_G8hZYcKnI

#include<bits/stdc++.h>
using namespace std;

int interval(vector<int>st, vector<int>ft, int n)
{
    int i = 1, j = 0, dorker = 1, r = 1;

    while(i < n && j < n)
    {
        if(st[i] < ft[j])
        {
            dorker++;
            i++;

            if(dorker > r)
            {
                r = dorker;
            }
        }
        else
        {
            dorker--;
            j++;
        }
    }

    return r;
}

int main()
{
    int n, i;

    cout << "Enter Schedule Number :: ";
    cin >> n;

    vector<int>start(n), finish(n);

    cout << "\nEnter Start And Finish Time :: \n";
    for(i=0;i<n;i++)
    {
        cin >> start[i] >> finish[i];
    }

    sort(start.begin(), start.end());
    sort(finish.begin(), finish.end());

    cout << "\nTotal Class Required :: " << interval(start, finish, n) << "\n";

    return 0;
}