一个理发店有一张可以坐N人的沙发和n个理发椅和n个理发师和一个收银员。没有顾客时，理发师睡觉，当一个顾客走进理发店时，如果沙发被坐满，则离开，否则，如果所有理发师正在为其他顾客理发，便在沙发上坐下等待。如果理发师正在睡觉，顾客需将他唤醒。理发完后顾客需付费直到收银员收费才能离开；

用类C语言编写程序

int count = 0; //the number of customers sit on sofaint chair = n;bool mutex = 1; // control the countbool mutex2 = 1; //control the cashier only deal with a customerint bnum = n; // the number of resting barberint cnum = 0; // the number of the customer sit in chairs int payment = 0;int receipt = 0; void barber() {    wait(cnum);    haircut for the customer;    signal(bnum);}void customer() {    wait(mutex);    if(count >= N) { // the sofa is full         signal(mutex);        leave;    }    else {        count++;        signal(mutex);                wait(chair); // wait for the empty chairs            count--;  // leave the sofa        signal(cnum);        wait(bnum); //wait for the barber        haircut;        signal(chair);                wait(mutex2);  //wait for the cashier        signal(payment);        pay;        wait(receipt);        leave;    }}void cashier() {    wait(payment);    receive payment;    signal(receipt);    signal(mutex2);}