RESTAURANT EXERCISE

Your restaurant has a set of tables of different sizes: each table can accommodate 2, 3, 4, 5 or 6 persons. Clients arrive alone or in groups, up to 6 persons. Clients within a given group must be seated together at one table, hence you can direct a group only to a table, which can accommodate them all. If there is no table with the required number of empty chairs, the group has to wait in the queue.

Once seated, the group cannot change the table, i.e. you cannot move a group from one table to another to make room for new clients.

Client groups must be served in the order of arrival with one exception: if there is enough room at a table for a smaller group arriving later, you can seat them before the larger group(s) in the queue. For example, if there is a six-person group waiting for a six-seat table and there is a two-person group queuing or arriving you can send them directly to a table with two empty chairs.

Groups may share tables, however if at the same time you have an empty table with the required number of chairs and enough empty chairs at a larger one, you must always seat your client(s) at an empty table and not any partly seated one, even if the empty table is bigger than the size of the group.

Of course the system assumes that any bigger group may get bored of seeing smaller groups arrive and get their tables ahead of them, and then decide to leave, which would mean that they abandon the queue without being served.

Please fill RestManager class with appropriate data structures and implement its constructor and three public methods. You are encouraged modify other classes too (to help us test them) and add new methods at your will.

public class Table 
{ 
   public final int size; // number of chairs 
} 

public class ClientsGroup
{
   public final int size; // number of clients
}

public class RestManager
{
   public RestManager (List<Table> tables)
   {
      // TODO
   }

   // new client(s) show up
   public void onArrive (ClientsGroup group)
   {
      // TODO
   }

   // client(s) leave, either served or simply abandoning the queue
   public void onLeave (ClientsGroup group)
   {
      // TODO
   }

   // return table where a given client group is seated, 
   // or null if it is still queuing or has already left
   public Table lookup (ClientsGroup group)
   {
      // TODO
   }
}