thread.c

#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
#include <semaphore.h>

sem_t even_lock, odd_lock;
pthread_mutex_t even_mutex, odd_mutex;

void * even_thread(void *args) {
   int i = 0;
   while (i < 10) {
      sem_wait(&even_lock);
      sleep(random()%3);
      printf("%d\n", i);
      i+=2;
      sem_post(&odd_lock);
    }
    pthread_exit(0);
}

void * odd_thread(void *args) {
    int i = 1;
    while (i < 10) {
        sem_wait(&odd_lock);
        sleep(random()%4);
        printf("%d\n", i);
        i+=2;
        sem_post(&even_lock);
    }
    pthread_exit(0);
}


void * even_thread2(void *args) {
   int i = 0;
   while (i < 10) {
      pthread_mutex_lock(&even_mutex);
      sleep(random()%3);
      printf("%d\n", i);
      i+=2;
      pthread_mutex_unlock(&odd_mutex);
    }
    pthread_exit(0);
}

void * odd_thread2(void *args) {
    int i = 1;
    while (i < 10) {
        pthread_mutex_lock(&odd_mutex);
        sleep(random()%4);
        printf("%d\n", i);
        i+=2;
        pthread_mutex_unlock(&even_mutex);
    }
    pthread_exit(0);
}

int main() {
     pthread_t thread[2];
     sem_init(&even_lock, 0, 1);
     sem_init(&odd_lock, 0, 0);

     printf("Solution semaphores:\n");
     pthread_create(&thread[0], NULL, even_thread, NULL);
     pthread_create(&thread[1], NULL, odd_thread, NULL);
     pthread_join(thread[0], NULL);
     pthread_join(thread[1], NULL);


     pthread_mutex_init(&even_mutex, NULL);
     pthread_mutex_init(&odd_mutex, NULL);

     printf("Solution mutexes:\n");
     pthread_create(&thread[0], NULL, even_thread2, NULL);
     pthread_create(&thread[1], NULL, odd_thread2, NULL);
     pthread_join(thread[0], NULL);
     pthread_join(thread[1], NULL);


     sem_destroy(&even_lock);
     sem_destroy(&odd_lock);
     pthread_mutex_destroy(&even_mutex);
     pthread_mutex_destroy(&odd_mutex);
     return 0;
}