semaphore customers = 0;

semaphore barbers = 0;

semaphore cutting = 0;

semaphore mutex = 1;

int customer1 = 0;

void barber() {

while(true) {

wait(customers); //they can sleep at the time  there are no waiting

wait(mutex); //mutex for accessing customers1

customers1 = customers1 - 1; signal(barbers);

signal(mutex);

cut_hair();

} } void customer() {

wait(mutex); //mutex for accessing customers1

if (customers1 < n) {

customers1 = customers1 + 1; signal(customers);

signal(mutex);

wait(barbers); //wait for available barbers

get_haircut();

}

else { //do nothing (leave) when all chairs are used.

signal(mutex);

}

}

cut_hair(){ waiting(cutting); } get_haircut(){

get hair cut for some time; signal(cutting);

}