#ifndef GRAPH_H
#define GRAPH_H

/* adjacency list implementation */

struct edge;

struct vertex
{
  struct edge *adj; /* edges linked list */
};

struct edge /* probably not a good name for this */
{
  struct vertex *to; /* other vertex in edge */
  struct edge *next;
};

struct graph
{
  struct vertex *v; /* array of vertices */
  unsigned int nv;  /* number of vertices */
};

struct graph *new_graph (unsigned int nv);
void free_graph (struct graph *g);

int add_arc (struct graph *g, unsigned int vi, unsigned int vj);
void del_arc (struct graph *g, unsigned int vi, unsigned int vj);

int add_edge (struct graph *g, unsigned int vi, unsigned int vj);
void del_edge (struct graph *g, unsigned int vi, unsigned int vj);

static __inline__ unsigned int
vertex_id (struct graph *g, struct vertex *v)
{
  return (unsigned int)(v - g->v);
}

#endif /* GRAPH_H  */