int schedule_lecture(classroomT classrooms_array[], courseT* course, const int duration){

    int i, j, k, l, availability_flag,m;

    for (i = 0; i < MAX_ROOMS; i++) {

        if (course != NULL && course -> enrolled_count <= classrooms_array[i].capacity) {
            for (j = 0; j < WORKING_HOURS; j++) {
                /* Lecture shouldn't last over working hours */
                if (j + duration > WORKING_HOURS) {
                    break;
                }

                for (k = 0; k < WORKING_DAYS; k++) {
                    availability_flag = 1;
                    for (l = j; l < j+duration; l++) {
                        if (classrooms_array[i].schedule[l][k] != NULL) {
                            availability_flag = 0;
                            break;
                        }
                    }

                    if(availability_flag){
                        /* Checking if the professor has a lecture in another classroom */
                        for(m=0; m<MAX_ROOMS; m++){
                            for (l = j; l < j+duration; l++) {
                                if (classrooms_array[m].schedule[l][k] != NULL   && !strcmp(classrooms_array[m].schedule[l][k]->prof_name,course->prof_name)) {
                                    availability_flag = 0;
                                    break;
                                }
                            }
                        }
                    }
                    /* If an available slot is found, set all pointers of that time slot towards the course */
                    if (availability_flag) {
                        for (l = j; l < j+duration; l++) {
                            classrooms_array[i].schedule[l][k] = course;
                        }
                        return i;
                    }
                }
            }
        }
    }
    return -1;
}