graph/adj.c

   1 #include "graph/adj.h"
   2 #include <errno.h>
   3 #include <stdlib.h>
   4
   5 struct graph *
   6 new_graph (unsigned int nv)
   7 {
   8   struct graph *g;
   9
  10   if (!nv)
  11     {
  12       errno = EINVAL;
  13       return NULL;
  14     }
  15
  16   if (!(g = malloc (sizeof *g)))
  17     return NULL;
  18
  19   g->nv = nv;
  20
  21   if (!(g->v = calloc (nv, sizeof *g->v)))
  22     {
  23       free (g);
  24       return NULL;
  25     }
  26
  27   return g;
  28 }
  29
  30 int
  31 new_arc (struct graph *g, unsigned int vi, unsigned int vj)
  32 {
  33   struct edge *e;
  34
  35   if (vi >= g->nv || vj >= g->nv)
  36     return -(errno = EINVAL);
  37
  38   if (!(e = malloc (sizeof *e)))
  39     return -errno;
  40
  41   e->to = &g->v[vj];
  42   e->next = g->v[vi].adj;
  43   g->v[vi].adj = e;
  44
  45   return 0;
  46 }
  47
  48 int
  49 new_edge (struct graph *g, unsigned int vi, unsigned int vj)
  50 {
  51   int err;
  52
  53   if (vi == vj)
  54     return -(errno = EINVAL);
  55
  56   if ((err = new_arc (g, vi, vj)))
  57     return err;
  58
  59   if ((err = new_arc (g, vj, vi)))
  60     return err;
  61
  62   return 0;
  63 }