graph/adj.c

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