1353. Maximum Number of Events That Can Be Attended

class Solution {
    public int maxEvents(int[][] events) {
        Arrays.sort(events,(a,b)->a[0]-b[0]);

        int day=0,index=0,n=events.length,result=0;

        PriorityQueue<Integer> pq = new PriorityQueue<>();

        while(!pq.isEmpty() || index<n){
            if(pq.isEmpty()){
                day = events[index][0];
            }
            while(index<n && events[index][0]<=day){
                pq.offer(events[index][1]);
                index++;
            }
            pq.poll();
            day++;
            result++;
            while(!pq.isEmpty() && pq.peek()<day){
                pq.poll();
            }
        }
        return result;
    }
}