public int findMinimumMeetingRooms(List<Meeting> meetings) {
    int n = meetings.size();
    int[] starr = new int[n], endarr = new int[n];
    for(int i = 0; i < n; i++) {
      starr[i] = meetings.get(i).start;
      endarr[i] = meetings.get(i).end;
    }

    Arrays.sort(starr);
    Arrays.sort(endarr);

    int  i = 0, j = 0, count = 0, max = 0;
    while(i < n && j < n) {
      if(starr[i] < endarr[j]) { // meeting started
        count++;
        i++;
      } else { // meeting ends
        count--;
        j++;
      }
      max = Math.max(count, max); // max no of rooms occupied right now
    }

    return max;
  }