#include <stdio.h>
#include <unistd.h>
#include <pthread.h>
#define NUM_DRIVERS  3
#define NUM_MUTEXES 3
pthread_mutex_t mutex[NUM_MUTEXES];

void *driving(void * buyer){
    int num_cars ;
    int buyer_num = *(int*)buyer;
    while(1) {
        for (num_cars = 0; num_cars < NUM_MUTEXES; num_cars ++)
        {
            if(pthread_mutex_trylock(&mutex[num_cars]))
            {
                printf("Buyer %d takes car %d.\n",buyer_num + 1, num_cars + 1);
                sleep(0.5);
                printf("Buyer %d returns car %d.\n",buyer_num + 1, num_cars + 1);
                pthread_mutex_unlock(&mutex[num_cars]);
            }
        }
    }
    return NULL;
}

int main () {
    pthread_t driver[NUM_DRIVERS];
    int rc;
    int num_drivers, num_threads;
    for(num_threads = 0 ; num_threads < NUM_MUTEXES ; num_threads++)
    {
        if(pthread_mutex_init (&mutex[num_threads], NULL))
        {
            printf("ERROR initing mutex");
            return 0;
        }
    }

    for(num_drivers = 0 ; num_drivers < NUM_DRIVERS; num_drivers++)
    {
        rc = pthread_create(&driver[num_drivers], NULL, driving, &num_drivers);
        if(rc)
        {
            printf("ERROR creating thread\n");
            return 0;
        }
    }

    for (num_drivers = 0 ; num_drivers < NUM_DRIVERS; num_drivers++)
    {
        if(pthread_join(driver[num_drivers], NULL))
        {
            printf("ERROR joining threads");
            return 0;
        }
    }

    for(num_threads = 0 ; num_threads < NUM_MUTEXES ; num_threads++)
    {
        if(pthread_mutex_destroy (&mutex[num_threads]))
        {
            printf("ERROR destroying mutex");
            return 0;
        }

    }


    return 0;
}