/*                                                                    aiutils.h
                                                                             */
struct city_list_link
{ city_record *this;
  struct city_list_link *next; };

typedef struct
{ struct city_list_link *first, *last;
  int num_entries; } list_of_cities;

struct road_list_link
{ road_record *this;
  struct road_list_link *next; };

typedef struct
{ struct road_list_link *first, *last;
  float total_length;
  int num_entries; } list_of_roads;

typedef struct
{ list_of_roads *route;
  city_record *from, *to; } state;

struct state_set_link
{ state *this;
  struct state_set_link *next; };

typedef struct
{ struct state_set_link *links;
  int size; } set_of_states;

list_of_cities *empty_list_of_cities(void);
int is_city_list_empty(list_of_cities *list);
int number_of_cities_in_list(list_of_cities *list);
void add_city_to_front_of_list(list_of_cities *list, city_record *city);
city_record *first_city_in_list(list_of_cities *list);
city_record *remove_first_city_from_list(list_of_cities *list);
void add_city_to_end_of_list(list_of_cities *list, city_record *city);
city_record *last_city_in_list(list_of_cities *list);
list_of_roads *empty_list_of_roads(void);
void print_list_of_roads(list_of_roads *list);
int is_road_list_empty(list_of_roads *list);
int number_of_roads_in_list(list_of_roads *list);
float total_length_of_path(list_of_roads *list);
void add_road_to_front_of_list(list_of_roads *list, road_record *road);
road_record *first_road_in_list(list_of_roads *list);
road_record *remove_first_road_from_list(list_of_roads *list);
void add_road_to_end_of_list(list_of_roads *list, road_record *road);
road_record *last_road_in_list(list_of_roads *list);
int is_empty_set(set_of_states *set);
set_of_states *empty_set(void);
void add_to_set(set_of_states *set, state *addition);
int size_of_set(set_of_states *set);
state *remove_random_member_from_set(set_of_states *set);
state *new_state(city_record *from, city_record *to);
state *duplicate_state(state *orig);
list_of_roads *duplicate_list_of_roads(list_of_roads *orig); 
list_of_cities *duplicate_list_of_cities(list_of_cities *orig); 
int city_appears_in_list_of_roads(list_of_roads *lr, city_record *c);