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Another classical problem takes place in a barber shop. This
problem is due to Dijkstra. The barber shop has one barber,
a barber chair, and n chairs for waiting customers, if any, to
sit on. If there are no customers present, the barber sits down
in the barber chair and falls asleep. When a customer arrives,
he has to wake up the sleeping barber. If additional customers
arrive while the barber is cutting a customer's hair, then they
sit down (if there are empty chairs) or leave the shop (if all
chairs are full). The problem is how to program the barber
and the customers without getting into race conditions. In your solution, you may want to introduce a class Shop. The Shop object has-a Barber object. A Barber
object is-a Thread object. The run method of the
Barber class should give rise to the output
The barber sits down and falls asleep and
The barber wakes up, whenever appropriate. In your
solution, you may also want to introduce a class
Customer. A Customer object is-a Thread.
The run method of the Customer class should
give rise to the output Customer i enters,
Customer i sits down (if there is an empty
chair), Customer i gets a haircut (if there
is an empty chair and once it is his turn), and
Customer i leaves.