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

sem_t *sems[6];

typedef struct params {
	int sPrev; 
	int sNext;
	int nPrev;
	int nNext;
	char * name;
} *params_t;

void* t_code(void * arg) {
	params_t p = (params_t) arg;
	while (1) {
		for (int i = 0; i < p->nPrev; i++) sem_wait(sems[p->sPrev]);
		puts(p->name);
		sleep(3);
		for (int i = 0; i < p->nNext; i++) sem_post(sems[p->sNext]);
	}
	free(p);
}

pthread_t* start_t(int sPrev, int sNext, int nPrev, int nNext, char * name) {
	pthread_t *t;
	params_t p = malloc(sizeof(struct params));
	p->sPrev = sPrev;
	p->sNext = sNext;
	p->nPrev = nPrev;
	p->nNext = nNext;
	p->name = name;
	pthread_create(t, NULL, t_code, (void *) p);
	return t;
}

int main() {
	for (int i = 0; i < 6; i++) {
		sems[i] = malloc(sizeof(sem_t)); 
		sem_init(sems[i], 0, 0);
	}
	sem_post(sems[0]);
	start_t(0, 1, 1, 3, "A");
	start_t(1, 2, 1, 1, "B");
	start_t(1, 3, 1, 2, "C");
	start_t(1, 4, 1, 1, "D");
	start_t(3, 5, 1, 1, "E");
	start_t(3, 5, 1, 1, "F");
	start_t(5, 2, 1, 1, "G");
	start_t(4, 2, 1, 1, "H");
	start_t(2, 0, 3, 1, "I");

	sleep(24);
}