#include <stdio.h>
#include <pthread.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>

pthread_mutex_t lock[3];

void *client(void *arg) {
    int num = *((int *) arg) + 1;
    int carsused[3] = {0, 0, 0};
    while (!(carsused[0] == 1 && carsused[1] == 1 && carsused[2] == 1))
    {
        for (int i = 0; i < 3; i++)
        {
            if (carsused[i] == 0)
            {
                if (pthread_mutex_trylock(&lock[i]) == 0)
                {

                    printf("** Buyer %d takes car %d.\n", num, i+1);
                    sleep(1);
                    printf("** Buyer %d returns car %d.\n", num, i+1);
                    pthread_mutex_unlock(&lock[i]);
                    carsused[i] = 1;
                }
            }
        }
    }

    pthread_exit(NULL);
    return 0;
}

int main() {

    pthread_t clients[3];
    int *clients_id = malloc(4 * sizeof(int*) );

    int i;

    for (i = 0;i<3;i++)
    {
        clients_id[i] = i;
        if (pthread_mutex_init(&lock[i], NULL) != 0)
        {
            printf("\n mutex init failed\n");
            return 1;
        }
        pthread_create(&clients[i],NULL,client, &clients_id[i]);
    }

    for (i = 0;i<3;i++)
    {
        pthread_mutex_destroy(&lock[i]);
        pthread_join(clients[i],NULL);
    }
    free(clients_id);

    return 0;
}