Minimum number of platforms required

class Solution {

    // Function to find the minimum number of platforms required at the

    // railway station such that no train waits.

    static int findPlatform(int arr[], int dep[]) {

        //sort the trains on the basis of arrival time of each train

        PriorityQueue<Schedule> q = new PriorityQueue<>((a,b)-> a.a-b.a);



        for(int i =0;i<arr.length;i++){

            q.add(new Schedule(arr[i],dep[i]));

        }

        //sort the trains on the basis of which train will leave first once they have 

        //been arrived (which is done on the basis of ascending order of depart time of the trains)

        Queue<Integer> trackDepart = new PriorityQueue<>();

        int noOfplatform = 1;// at min we will need 1 platform

        while(!q.isEmpty()){

            Schedule s = q.remove();// train arrived 

            if(!trackDepart.isEmpty()){

                if(trackDepart.peek() < s.a){ // if the arrival time of the train is greater than the 

                //train that will depart first then new train can arrive on the same platfrom (no increment in the platfrom no.)

                    trackDepart.remove(); // old train will go

                }

                else{

                    noOfplatform++;// else new train will need to come in a different platform

                }

            }

            trackDepart.add(s.d);// add the depat time of the new train the queue to check for the next train if that can arrive on the same of new platform will be needed 

        }

        return noOfplatform;

    }

}

class Schedule{

    public int a;

    public int d;

    public Schedule(int a, int d){

        this.a = a;

        this.d=  d;

    }

}