1.        2列火车

#include<myhead.h>

pthread_mutex_t m1;
pthread_mutex_t m2;

void* run(void* arg)
{
	while(1)
	{
		pthread_mutex_lock(&m1);
		printf("火车B进入\n");
		printf("A请等待\n");
		pthread_mutex_unlock(&m2);
		sleep(2);
	}
}

int main(int argc, const char *argv[])
{

	pthread_t id;
	pthread_create(&id,NULL,run,NULL);
	pthread_detach(id);

	pthread_mutex_init(&m1,NULL);
	pthread_mutex_init(&m2,NULL);
	pthread_mutex_lock(&m1);

	while(1)
	{
		pthread_mutex_lock(&m2);
		printf("火车A进入\n");
		printf("B请等待\n");
		pthread_mutex_unlock(&m1);
		sleep(1);
	}

	return 0;
}

2.     3列火车

#include<myhead.h>

pthread_mutex_t m1;
pthread_mutex_t m2;
pthread_mutex_t m3;

void* run1(void* arg)
{
	while(1)
	{
		pthread_mutex_lock(&m2);
		printf("火车B进入\n");
		printf("C请等待\n");
		pthread_mutex_unlock(&m3);
		sleep(2);
	}
}
void* run2(void* arg)
{
	while(1)
	{
		pthread_mutex_lock(&m3);
		printf("火车C进入\n");
		printf("A请等待\n");
		pthread_mutex_unlock(&m1);
		sleep(4);
	}
}

int main(int argc, const char *argv[])
{

	pthread_t id1;
	pthread_create(&id1,NULL,run1,NULL);
	pthread_detach(id1);
	pthread_t id2;
	pthread_create(&id2,NULL,run2,NULL);
	pthread_detach(id2);

	pthread_mutex_init(&m1,NULL);
	pthread_mutex_init(&m2,NULL);
	pthread_mutex_init(&m3,NULL);
	pthread_mutex_lock(&m3);

	while(1)
	{
		pthread_mutex_lock(&m1);
		printf("火车A进入\n");
		printf("B请等待\n");
		pthread_mutex_unlock(&m2);
		sleep(1);
	}

	return 0;
}