Traffic Control: Solution

/*NS-cars_sol.c*/
#include <fcntl.h>
#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>

int main(int argc, char *argv[]) {
    int i, car = 0, loop = 3;
    sem_t *ns, *ew;
    ns = sem_open("ns", O_CREAT, 0666, 1);
    ew = sem_open("ew", O_CREAT, 0666, 0);
    for (i = 0; i < loop; i++) {
        sem_wait(ns);
        printf("Semaphore: The road from north to south is open\n");
        sleep(1);
        printf("NS-Car: car %d passed\n", car++);
        sem_post(ew);
    }
    printf("NS: Time is up. %d cars passed.\n", car);

    sem_close(ns);
    sem_close(ew);
    sem_unlink("ns");
    sem_unlink("ew");

    return 0;
}

/*EW-cars_sol.c*/
#include <fcntl.h>
#include <semaphore.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>

int main(int argc, char *argv[]) {
    int i, car = 0, loop = 3;
    sem_t *ns, *ew;

    ns = sem_open("ns", O_CREAT, 0666, 1);
    ew = sem_open("ew", O_CREAT, 0666, 0);
    for (i = 0; i < loop; i++) {
        sem_wait(ew);
        printf("Semaphore: The road from east to west is open\n");
        sleep(rand() % 2 + 1);
        printf("EW-Car: car %d passed\n", car++);
        sem_post(ns);
    }
    printf("EW: Time is up. %d cars passed.\n", car);

    sem_close(ns);
    sem_close(ew);
    sem_unlink("ns");
    sem_unlink("ew");

    return 0;
}