理发师问题

int chairs = n;semaphore cust = 0;semaphore mutex = 1;int waiting = 0;cust(){    p(mutex);if(waiting < chairs){       waiting ++;       v(cust);       v(mutex);       p(barber);       hair-cut();}else{  v(mutex);}}

semaphore barber = 0;barber(){while(true){  p(cust);  p(mutex);  waiting --;  v(barber);  v(mutex); }}