Core Rules

• Rooms are identified by integer IDs: 0 to roomsCount - 1.
• Employees are identified by integer IDs: 0 to employeesCount - 1.
• A booking reserves exactly one room for exactly one employee during a time interval.
• Time interval convention: treat a booking as [startTime, endTime].
  • Both startTime and endTime are inclusive
  • This means: Meeting intervals [10, 20] and [20, 30] do overlap each other.
• No double-booking: the same room cannot have overlapping bookings.

Methods

• constructor: MeetingRoomScheduler(int roomsCount, int employeesCount)
  Initializes an in-memory scheduler with a fixed set of rooms and employees.
  • roomsCount > 0, employeesCount > 0.
  • room ids's are between 0 and roomsCount-1
  • employee id's are between 0 and employeesCount-1
• boolean bookRoom(String bookingId, int employeeId, int roomId, int startTime, int endTime)
  Attempts to create a booking for the given room and employee.
  • bookingId is always unique and non-blank.
  • employeeId and roomId are always valid.
  • Invalid time range: if startTime > endTime, or startTime<0 then return false.
  • If the room has no overlapping booking in [startTime, endTime], create the booking and return true.
  • If the room already has an overlapping booking, return false (do not partially add anything).
• List<Integer> getAvailableRooms(int startTime, int endTime)
  Returns the list of room IDs that are free for the entire interval.
  • Invalid time range: if startTime > endTime, return an empty list.
  • Return room IDs in ascending order.
• boolean cancelBooking(String bookingId)
  Cancels an existing booking by its ID.
  • Return true if a booking with this ID existed and was removed.
  • Return false if the booking ID does not exist (no-op).
• List<String> listBookingsForRoom(int roomId)
  Returns a list of booking IDs for that room (or empty list).
  • Return booking IDs sorted by startTime and then by bookingId in ascending order.
• List<String> listBookingsForEmployee(int employeeId)
  Returns a list of booking IDs for that employee (or empty list).
  • Return booking IDs sorted by startTime and then by bookingId in ascending order.

Examples:

Example 1: Availability, overlap (same room), boundary conflict, different-room overlap, cancel, listing

MeetingRoomScheduler s = new MeetingRoomScheduler(2, 2);  // rooms: 0,1  employees: 0,1

s.getAvailableRooms(10, 20)
=> [0, 1]

s.bookRoom("b1", 0, 0, 10, 20)
=> true

s.bookRoom("b2", 1, 0, 15, 25)
=> false   // same room overlap

s.bookRoom("b3", 1, 0, 20, 30)
=> false   // boundary overlaps because intervals are CLOSED (time=20 is shared)

s.bookRoom("b4", 1, 0, 21, 30)
=> true    // no overlap with [10,20]

s.bookRoom("b5", 0, 1, 15, 25)
=> true    // allowed: different room can overlap in time

s.getAvailableRooms(20, 20)
=> []      // at time=20: room0 busy (b1), room1 busy (b5)

s.listBookingsForRoom(0)
=> ["b1", "b4"]

s.listBookingsForRoom(1)
=> ["b5"]

s.listBookingsForEmployee(0)
=> ["b1", "b5"]

s.listBookingsForEmployee(1)
=> ["b4"]

s.cancelBooking("b2")
=> false   // booking never existed

s.cancelBooking("b1")
=> true

s.cancelBooking("b1")
=> false   // already cancelled

s.getAvailableRooms(10, 20)
=> [0]     // room0 now free for [10,20]; room1 still overlaps due to b5
  

Example 2: Edge cases: invalid interval, instant booking, “no rooms available”, cancel non-existent

MeetingRoomScheduler s = new MeetingRoomScheduler(1, 1);  // room: 0  employee: 0

s.listBookingsForRoom(0)
=> []

s.listBookingsForEmployee(0)
=> []

s.bookRoom("x1", 0, 0, 50, 49)
=> false   // invalid: startTime > endTime

s.getAvailableRooms(70, 10)
=> []      // invalid query interval

s.bookRoom("x2", 0, 0, 60, 60)
=> true    // valid instant booking at time=60 (closed interval)

s.getAvailableRooms(60, 60)
=> []      // room0 is busy at time=60

s.bookRoom("x3", 0, 0, 61, 61)
=> true    // does NOT overlap with [60,60]

s.bookRoom("x4", 0, 0, 60, 61)
=> false   // overlaps with x2 at 60 AND x3 at 61 (closed interval)

s.cancelBooking("does-not-exist")
=> false

s.cancelBooking("x2")
=> true

s.getAvailableRooms(60, 60)
=> [0]     // now free at time=60