alpar@1: /* glpapi15.c (basic graph and network routines) */
alpar@1: 
alpar@1: /***********************************************************************
alpar@1: *  This code is part of GLPK (GNU Linear Programming Kit).
alpar@1: *
alpar@1: *  Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
alpar@1: *  2009, 2010 Andrew Makhorin, Department for Applied Informatics,
alpar@1: *  Moscow Aviation Institute, Moscow, Russia. All rights reserved.
alpar@1: *  E-mail: <mao@gnu.org>.
alpar@1: *
alpar@1: *  GLPK is free software: you can redistribute it and/or modify it
alpar@1: *  under the terms of the GNU General Public License as published by
alpar@1: *  the Free Software Foundation, either version 3 of the License, or
alpar@1: *  (at your option) any later version.
alpar@1: *
alpar@1: *  GLPK is distributed in the hope that it will be useful, but WITHOUT
alpar@1: *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
alpar@1: *  or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
alpar@1: *  License for more details.
alpar@1: *
alpar@1: *  You should have received a copy of the GNU General Public License
alpar@1: *  along with GLPK. If not, see <http://www.gnu.org/licenses/>.
alpar@1: ***********************************************************************/
alpar@1: 
alpar@1: #include "glpapi.h"
alpar@1: 
alpar@1: /* CAUTION: DO NOT CHANGE THE LIMITS BELOW */
alpar@1: 
alpar@1: #define NV_MAX 100000000 /* = 100*10^6 */
alpar@1: /* maximal number of vertices in the graph */
alpar@1: 
alpar@1: #define NA_MAX 500000000 /* = 500*10^6 */
alpar@1: /* maximal number of arcs in the graph */
alpar@1: 
alpar@1: /***********************************************************************
alpar@1: *  NAME
alpar@1: *
alpar@1: *  glp_create_graph - create graph
alpar@1: *
alpar@1: *  SYNOPSIS
alpar@1: *
alpar@1: *  glp_graph *glp_create_graph(int v_size, int a_size);
alpar@1: *
alpar@1: *  DESCRIPTION
alpar@1: *
alpar@1: *  The routine creates a new graph, which initially is empty, i.e. has
alpar@1: *  no vertices and arcs.
alpar@1: *
alpar@1: *  The parameter v_size specifies the size of data associated with each
alpar@1: *  vertex of the graph (0 to 256 bytes).
alpar@1: *
alpar@1: *  The parameter a_size specifies the size of data associated with each
alpar@1: *  arc of the graph (0 to 256 bytes).
alpar@1: *
alpar@1: *  RETURNS
alpar@1: *
alpar@1: *  The routine returns a pointer to the graph created. */
alpar@1: 
alpar@1: static void create_graph(glp_graph *G, int v_size, int a_size)
alpar@1: {     G->pool = dmp_create_pool();
alpar@1:       G->name = NULL;
alpar@1:       G->nv_max = 50;
alpar@1:       G->nv = G->na = 0;
alpar@1:       G->v = xcalloc(1+G->nv_max, sizeof(glp_vertex *));
alpar@1:       G->index = NULL;
alpar@1:       G->v_size = v_size;
alpar@1:       G->a_size = a_size;
alpar@1:       return;
alpar@1: }
alpar@1: 
alpar@1: glp_graph *glp_create_graph(int v_size, int a_size)
alpar@1: {     glp_graph *G;
alpar@1:       if (!(0 <= v_size && v_size <= 256))
alpar@1:          xerror("glp_create_graph: v_size = %d; invalid size of vertex "
alpar@1:             "data\n", v_size);
alpar@1:       if (!(0 <= a_size && a_size <= 256))
alpar@1:          xerror("glp_create_graph: a_size = %d; invalid size of arc dat"
alpar@1:             "a\n", a_size);
alpar@1:       G = xmalloc(sizeof(glp_graph));
alpar@1:       create_graph(G, v_size, a_size);
alpar@1:       return G;
alpar@1: }
alpar@1: 
alpar@1: /***********************************************************************
alpar@1: *  NAME
alpar@1: *
alpar@1: *  glp_set_graph_name - assign (change) graph name
alpar@1: *
alpar@1: *  SYNOPSIS
alpar@1: *
alpar@1: *  void glp_set_graph_name(glp_graph *G, const char *name);
alpar@1: *
alpar@1: *  DESCRIPTION
alpar@1: *
alpar@1: *  The routine glp_set_graph_name assigns a symbolic name specified by
alpar@1: *  the character string name (1 to 255 chars) to the graph.
alpar@1: *
alpar@1: *  If the parameter name is NULL or an empty string, the routine erases
alpar@1: *  the existing symbolic name of the graph. */
alpar@1: 
alpar@1: void glp_set_graph_name(glp_graph *G, const char *name)
alpar@1: {     if (G->name != NULL)
alpar@1:       {  dmp_free_atom(G->pool, G->name, strlen(G->name)+1);
alpar@1:          G->name = NULL;
alpar@1:       }
alpar@1:       if (!(name == NULL || name[0] == '\0'))
alpar@1:       {  int j;
alpar@1:          for (j = 0; name[j] != '\0'; j++)
alpar@1:          {  if (j == 256)
alpar@1:                xerror("glp_set_graph_name: graph name too long\n");
alpar@1:             if (iscntrl((unsigned char)name[j]))
alpar@1:                xerror("glp_set_graph_name: graph name contains invalid "
alpar@1:                   "character(s)\n");
alpar@1:          }
alpar@1:          G->name = dmp_get_atom(G->pool, strlen(name)+1);
alpar@1:          strcpy(G->name, name);
alpar@1:       }
alpar@1:       return;
alpar@1: }
alpar@1: 
alpar@1: /***********************************************************************
alpar@1: *  NAME
alpar@1: *
alpar@1: *  glp_add_vertices - add new vertices to graph
alpar@1: *
alpar@1: *  SYNOPSIS
alpar@1: *
alpar@1: *  int glp_add_vertices(glp_graph *G, int nadd);
alpar@1: *
alpar@1: *  DESCRIPTION
alpar@1: *
alpar@1: *  The routine glp_add_vertices adds nadd vertices to the specified
alpar@1: *  graph. New vertices are always added to the end of the vertex list,
alpar@1: *  so ordinal numbers of existing vertices remain unchanged.
alpar@1: *
alpar@1: *  Being added each new vertex is isolated (has no incident arcs).
alpar@1: *
alpar@1: *  RETURNS
alpar@1: *
alpar@1: *  The routine glp_add_vertices returns an ordinal number of the first
alpar@1: *  new vertex added to the graph. */
alpar@1: 
alpar@1: int glp_add_vertices(glp_graph *G, int nadd)
alpar@1: {     int i, nv_new;
alpar@1:       if (nadd < 1)
alpar@1:          xerror("glp_add_vertices: nadd = %d; invalid number of vertice"
alpar@1:             "s\n", nadd);
alpar@1:       if (nadd > NV_MAX - G->nv)
alpar@1:          xerror("glp_add_vertices: nadd = %d; too many vertices\n",
alpar@1:             nadd);
alpar@1:       /* determine new number of vertices */
alpar@1:       nv_new = G->nv + nadd;
alpar@1:       /* increase the room, if necessary */
alpar@1:       if (G->nv_max < nv_new)
alpar@1:       {  glp_vertex **save = G->v;
alpar@1:          while (G->nv_max < nv_new)
alpar@1:          {  G->nv_max += G->nv_max;
alpar@1:             xassert(G->nv_max > 0);
alpar@1:          }
alpar@1:          G->v = xcalloc(1+G->nv_max, sizeof(glp_vertex *));
alpar@1:          memcpy(&G->v[1], &save[1], G->nv * sizeof(glp_vertex *));
alpar@1:          xfree(save);
alpar@1:       }
alpar@1:       /* add new vertices to the end of the vertex list */
alpar@1:       for (i = G->nv+1; i <= nv_new; i++)
alpar@1:       {  glp_vertex *v;
alpar@1:          G->v[i] = v = dmp_get_atom(G->pool, sizeof(glp_vertex));
alpar@1:          v->i = i;
alpar@1:          v->name = NULL;
alpar@1:          v->entry = NULL;
alpar@1:          if (G->v_size == 0)
alpar@1:             v->data = NULL;
alpar@1:          else
alpar@1:          {  v->data = dmp_get_atom(G->pool, G->v_size);
alpar@1:             memset(v->data, 0, G->v_size);
alpar@1:          }
alpar@1:          v->temp = NULL;
alpar@1:          v->in = v->out = NULL;
alpar@1:       }
alpar@1:       /* set new number of vertices */
alpar@1:       G->nv = nv_new;
alpar@1:       /* return the ordinal number of the first vertex added */
alpar@1:       return nv_new - nadd + 1;
alpar@1: }
alpar@1: 
alpar@1: /**********************************************************************/
alpar@1: 
alpar@1: void glp_set_vertex_name(glp_graph *G, int i, const char *name)
alpar@1: {     /* assign (change) vertex name */
alpar@1:       glp_vertex *v;
alpar@1:       if (!(1 <= i && i <= G->nv))
alpar@1:          xerror("glp_set_vertex_name: i = %d; vertex number out of rang"
alpar@1:             "e\n", i);
alpar@1:       v = G->v[i];
alpar@1:       if (v->name != NULL)
alpar@1:       {  if (v->entry != NULL)
alpar@1:          {  xassert(G->index != NULL);
alpar@1:             avl_delete_node(G->index, v->entry);
alpar@1:             v->entry = NULL;
alpar@1:          }
alpar@1:          dmp_free_atom(G->pool, v->name, strlen(v->name)+1);
alpar@1:          v->name = NULL;
alpar@1:       }
alpar@1:       if (!(name == NULL || name[0] == '\0'))
alpar@1:       {  int k;
alpar@1:          for (k = 0; name[k] != '\0'; k++)
alpar@1:          {  if (k == 256)
alpar@1:                xerror("glp_set_vertex_name: i = %d; vertex name too lon"
alpar@1:                   "g\n", i);
alpar@1:             if (iscntrl((unsigned char)name[k]))
alpar@1:                xerror("glp_set_vertex_name: i = %d; vertex name contain"
alpar@1:                   "s invalid character(s)\n", i);
alpar@1:          }
alpar@1:          v->name = dmp_get_atom(G->pool, strlen(name)+1);
alpar@1:          strcpy(v->name, name);
alpar@1:          if (G->index != NULL)
alpar@1:          {  xassert(v->entry == NULL);
alpar@1:             v->entry = avl_insert_node(G->index, v->name);
alpar@1:             avl_set_node_link(v->entry, v);
alpar@1:          }
alpar@1:       }
alpar@1:       return;
alpar@1: }
alpar@1: 
alpar@1: /***********************************************************************
alpar@1: *  NAME
alpar@1: *
alpar@1: *  glp_add_arc - add new arc to graph
alpar@1: *
alpar@1: *  SYNOPSIS
alpar@1: *
alpar@1: *  glp_arc *glp_add_arc(glp_graph *G, int i, int j);
alpar@1: *
alpar@1: *  DESCRIPTION
alpar@1: *
alpar@1: *  The routine glp_add_arc adds a new arc to the specified graph.
alpar@1: *
alpar@1: *  The parameters i and j specify the ordinal numbers of, resp., tail
alpar@1: *  and head vertices of the arc. Note that self-loops and multiple arcs
alpar@1: *  are allowed.
alpar@1: *
alpar@1: *  RETURNS
alpar@1: *
alpar@1: *  The routine glp_add_arc returns a pointer to the arc added. */
alpar@1: 
alpar@1: glp_arc *glp_add_arc(glp_graph *G, int i, int j)
alpar@1: {     glp_arc *a;
alpar@1:       if (!(1 <= i && i <= G->nv))
alpar@1:          xerror("glp_add_arc: i = %d; tail vertex number out of range\n"
alpar@1:             , i);
alpar@1:       if (!(1 <= j && j <= G->nv))
alpar@1:          xerror("glp_add_arc: j = %d; head vertex number out of range\n"
alpar@1:             , j);
alpar@1:       if (G->na == NA_MAX)
alpar@1:          xerror("glp_add_arc: too many arcs\n");
alpar@1:       a = dmp_get_atom(G->pool, sizeof(glp_arc));
alpar@1:       a->tail = G->v[i];
alpar@1:       a->head = G->v[j];
alpar@1:       if (G->a_size == 0)
alpar@1:          a->data = NULL;
alpar@1:       else
alpar@1:       {  a->data = dmp_get_atom(G->pool, G->a_size);
alpar@1:          memset(a->data, 0, G->a_size);
alpar@1:       }
alpar@1:       a->temp = NULL;
alpar@1:       a->t_prev = NULL;
alpar@1:       a->t_next = G->v[i]->out;
alpar@1:       if (a->t_next != NULL) a->t_next->t_prev = a;
alpar@1:       a->h_prev = NULL;
alpar@1:       a->h_next = G->v[j]->in;
alpar@1:       if (a->h_next != NULL) a->h_next->h_prev = a;
alpar@1:       G->v[i]->out = G->v[j]->in = a;
alpar@1:       G->na++;
alpar@1:       return a;
alpar@1: }
alpar@1: 
alpar@1: /***********************************************************************
alpar@1: *  NAME
alpar@1: *
alpar@1: *  glp_del_vertices - delete vertices from graph
alpar@1: *
alpar@1: *  SYNOPSIS
alpar@1: *
alpar@1: *  void glp_del_vertices(glp_graph *G, int ndel, const int num[]);
alpar@1: *
alpar@1: *  DESCRIPTION
alpar@1: *
alpar@1: *  The routine glp_del_vertices deletes vertices along with all
alpar@1: *  incident arcs from the specified graph. Ordinal numbers of vertices
alpar@1: *  to be deleted should be placed in locations num[1], ..., num[ndel],
alpar@1: *  ndel > 0.
alpar@1: *
alpar@1: *  Note that deleting vertices involves changing ordinal numbers of
alpar@1: *  other vertices remaining in the graph. New ordinal numbers of the
alpar@1: *  remaining vertices are assigned under the assumption that the
alpar@1: *  original order of vertices is not changed. */
alpar@1: 
alpar@1: void glp_del_vertices(glp_graph *G, int ndel, const int num[])
alpar@1: {     glp_vertex *v;
alpar@1:       int i, k, nv_new;
alpar@1:       /* scan the list of vertices to be deleted */
alpar@1:       if (!(1 <= ndel && ndel <= G->nv))
alpar@1:          xerror("glp_del_vertices: ndel = %d; invalid number of vertice"
alpar@1:             "s\n", ndel);
alpar@1:       for (k = 1; k <= ndel; k++)
alpar@1:       {  /* take the number of vertex to be deleted */
alpar@1:          i = num[k];
alpar@1:          /* obtain pointer to i-th vertex */
alpar@1:          if (!(1 <= i && i <= G->nv))
alpar@1:             xerror("glp_del_vertices: num[%d] = %d; vertex number out o"
alpar@1:                "f range\n", k, i);
alpar@1:          v = G->v[i];
alpar@1:          /* check that the vertex is not marked yet */
alpar@1:          if (v->i == 0)
alpar@1:             xerror("glp_del_vertices: num[%d] = %d; duplicate vertex nu"
alpar@1:                "mbers not allowed\n", k, i);
alpar@1:          /* erase symbolic name assigned to the vertex */
alpar@1:          glp_set_vertex_name(G, i, NULL);
alpar@1:          xassert(v->name == NULL);
alpar@1:          xassert(v->entry == NULL);
alpar@1:          /* free vertex data, if allocated */
alpar@1:          if (v->data != NULL)
alpar@1:             dmp_free_atom(G->pool, v->data, G->v_size);
alpar@1:          /* delete all incoming arcs */
alpar@1:          while (v->in != NULL)
alpar@1:             glp_del_arc(G, v->in);
alpar@1:          /* delete all outgoing arcs */
alpar@1:          while (v->out != NULL)
alpar@1:             glp_del_arc(G, v->out);
alpar@1:          /* mark the vertex to be deleted */
alpar@1:          v->i = 0;
alpar@1:       }
alpar@1:       /* delete all marked vertices from the vertex list */
alpar@1:       nv_new = 0;
alpar@1:       for (i = 1; i <= G->nv; i++)
alpar@1:       {  /* obtain pointer to i-th vertex */
alpar@1:          v = G->v[i];
alpar@1:          /* check if the vertex is marked */
alpar@1:          if (v->i == 0)
alpar@1:          {  /* it is marked, delete it */
alpar@1:             dmp_free_atom(G->pool, v, sizeof(glp_vertex));
alpar@1:          }
alpar@1:          else
alpar@1:          {  /* it is not marked, keep it */
alpar@1:             v->i = ++nv_new;
alpar@1:             G->v[v->i] = v;
alpar@1:          }
alpar@1:       }
alpar@1:       /* set new number of vertices in the graph */
alpar@1:       G->nv = nv_new;
alpar@1:       return;
alpar@1: }
alpar@1: 
alpar@1: /***********************************************************************
alpar@1: *  NAME
alpar@1: *
alpar@1: *  glp_del_arc - delete arc from graph
alpar@1: *
alpar@1: *  SYNOPSIS
alpar@1: *
alpar@1: *  void glp_del_arc(glp_graph *G, glp_arc *a);
alpar@1: *
alpar@1: *  DESCRIPTION
alpar@1: *
alpar@1: *  The routine glp_del_arc deletes an arc from the specified graph.
alpar@1: *  The arc to be deleted must exist. */
alpar@1: 
alpar@1: void glp_del_arc(glp_graph *G, glp_arc *a)
alpar@1: {     /* some sanity checks */
alpar@1:       xassert(G->na > 0);
alpar@1:       xassert(1 <= a->tail->i && a->tail->i <= G->nv);
alpar@1:       xassert(a->tail == G->v[a->tail->i]);
alpar@1:       xassert(1 <= a->head->i && a->head->i <= G->nv);
alpar@1:       xassert(a->head == G->v[a->head->i]);
alpar@1:       /* remove the arc from the list of incoming arcs */
alpar@1:       if (a->h_prev == NULL)
alpar@1:          a->head->in = a->h_next;
alpar@1:       else
alpar@1:          a->h_prev->h_next = a->h_next;
alpar@1:       if (a->h_next == NULL)
alpar@1:          ;
alpar@1:       else
alpar@1:          a->h_next->h_prev = a->h_prev;
alpar@1:       /* remove the arc from the list of outgoing arcs */
alpar@1:       if (a->t_prev == NULL)
alpar@1:          a->tail->out = a->t_next;
alpar@1:       else
alpar@1:          a->t_prev->t_next = a->t_next;
alpar@1:       if (a->t_next == NULL)
alpar@1:          ;
alpar@1:       else
alpar@1:          a->t_next->t_prev = a->t_prev;
alpar@1:       /* free arc data, if allocated */
alpar@1:       if (a->data != NULL)
alpar@1:          dmp_free_atom(G->pool, a->data, G->a_size);
alpar@1:       /* delete the arc from the graph */
alpar@1:       dmp_free_atom(G->pool, a, sizeof(glp_arc));
alpar@1:       G->na--;
alpar@1:       return;
alpar@1: }
alpar@1: 
alpar@1: /***********************************************************************
alpar@1: *  NAME
alpar@1: *
alpar@1: *  glp_erase_graph - erase graph content
alpar@1: *
alpar@1: *  SYNOPSIS
alpar@1: *
alpar@1: *  void glp_erase_graph(glp_graph *G, int v_size, int a_size);
alpar@1: *
alpar@1: *  DESCRIPTION
alpar@1: *
alpar@1: *  The routine glp_erase_graph erases the content of the specified
alpar@1: *  graph. The effect of this operation is the same as if the graph
alpar@1: *  would be deleted with the routine glp_delete_graph and then created
alpar@1: *  anew with the routine glp_create_graph, with exception that the
alpar@1: *  handle (pointer) to the graph remains valid. */
alpar@1: 
alpar@1: static void delete_graph(glp_graph *G)
alpar@1: {     dmp_delete_pool(G->pool);
alpar@1:       xfree(G->v);
alpar@1:       if (G->index != NULL) avl_delete_tree(G->index);
alpar@1:       return;
alpar@1: }
alpar@1: 
alpar@1: void glp_erase_graph(glp_graph *G, int v_size, int a_size)
alpar@1: {     if (!(0 <= v_size && v_size <= 256))
alpar@1:          xerror("glp_erase_graph: v_size = %d; invalid size of vertex d"
alpar@1:             "ata\n", v_size);
alpar@1:       if (!(0 <= a_size && a_size <= 256))
alpar@1:          xerror("glp_erase_graph: a_size = %d; invalid size of arc data"
alpar@1:             "\n", a_size);
alpar@1:       delete_graph(G);
alpar@1:       create_graph(G, v_size, a_size);
alpar@1:       return;
alpar@1: }
alpar@1: 
alpar@1: /***********************************************************************
alpar@1: *  NAME
alpar@1: *
alpar@1: *  glp_delete_graph - delete graph
alpar@1: *
alpar@1: *  SYNOPSIS
alpar@1: *
alpar@1: *  void glp_delete_graph(glp_graph *G);
alpar@1: *
alpar@1: *  DESCRIPTION
alpar@1: *
alpar@1: *  The routine glp_delete_graph deletes the specified graph and frees
alpar@1: *  all the memory allocated to this program object. */
alpar@1: 
alpar@1: void glp_delete_graph(glp_graph *G)
alpar@1: {     delete_graph(G);
alpar@1:       xfree(G);
alpar@1:       return;
alpar@1: }
alpar@1: 
alpar@1: /**********************************************************************/
alpar@1: 
alpar@1: void glp_create_v_index(glp_graph *G)
alpar@1: {     /* create vertex name index */
alpar@1:       glp_vertex *v;
alpar@1:       int i;
alpar@1:       if (G->index == NULL)
alpar@1:       {  G->index = avl_create_tree(avl_strcmp, NULL);
alpar@1:          for (i = 1; i <= G->nv; i++)
alpar@1:          {  v = G->v[i];
alpar@1:             xassert(v->entry == NULL);
alpar@1:             if (v->name != NULL)
alpar@1:             {  v->entry = avl_insert_node(G->index, v->name);
alpar@1:                avl_set_node_link(v->entry, v);
alpar@1:             }
alpar@1:          }
alpar@1:       }
alpar@1:       return;
alpar@1: }
alpar@1: 
alpar@1: int glp_find_vertex(glp_graph *G, const char *name)
alpar@1: {     /* find vertex by its name */
alpar@1:       AVLNODE *node;
alpar@1:       int i = 0;
alpar@1:       if (G->index == NULL)
alpar@1:          xerror("glp_find_vertex: vertex name index does not exist\n");
alpar@1:       if (!(name == NULL || name[0] == '\0' || strlen(name) > 255))
alpar@1:       {  node = avl_find_node(G->index, name);
alpar@1:          if (node != NULL)
alpar@1:             i = ((glp_vertex *)avl_get_node_link(node))->i;
alpar@1:       }
alpar@1:       return i;
alpar@1: }
alpar@1: 
alpar@1: void glp_delete_v_index(glp_graph *G)
alpar@1: {     /* delete vertex name index */
alpar@1:       int i;
alpar@1:       if (G->index != NULL)
alpar@1:       {  avl_delete_tree(G->index), G->index = NULL;
alpar@1:          for (i = 1; i <= G->nv; i++) G->v[i]->entry = NULL;
alpar@1:       }
alpar@1:       return;
alpar@1: }
alpar@1: 
alpar@1: /***********************************************************************
alpar@1: *  NAME
alpar@1: *
alpar@1: *  glp_read_graph - read graph from plain text file
alpar@1: *
alpar@1: *  SYNOPSIS
alpar@1: *
alpar@1: *  int glp_read_graph(glp_graph *G, const char *fname);
alpar@1: *
alpar@1: *  DESCRIPTION
alpar@1: *
alpar@1: *  The routine glp_read_graph reads a graph from a plain text file.
alpar@1: *
alpar@1: *  RETURNS
alpar@1: *
alpar@1: *  If the operation was successful, the routine returns zero. Otherwise
alpar@1: *  it prints an error message and returns non-zero. */
alpar@1: 
alpar@1: int glp_read_graph(glp_graph *G, const char *fname)
alpar@1: {     glp_data *data;
alpar@1:       jmp_buf jump;
alpar@1:       int nv, na, i, j, k, ret;
alpar@1:       glp_erase_graph(G, G->v_size, G->a_size);
alpar@1:       xprintf("Reading graph from `%s'...\n", fname);
alpar@1:       data = glp_sdf_open_file(fname);
alpar@1:       if (data == NULL)
alpar@1:       {  ret = 1;
alpar@1:          goto done;
alpar@1:       }
alpar@1:       if (setjmp(jump))
alpar@1:       {  ret = 1;
alpar@1:          goto done;
alpar@1:       }
alpar@1:       glp_sdf_set_jump(data, jump);
alpar@1:       nv = glp_sdf_read_int(data);
alpar@1:       if (nv < 0)
alpar@1:          glp_sdf_error(data, "invalid number of vertices\n");
alpar@1:       na = glp_sdf_read_int(data);
alpar@1:       if (na < 0)
alpar@1:          glp_sdf_error(data, "invalid number of arcs\n");
alpar@1:       xprintf("Graph has %d vert%s and %d arc%s\n",
alpar@1:          nv, nv == 1 ? "ex" : "ices", na, na == 1 ? "" : "s");
alpar@1:       if (nv > 0) glp_add_vertices(G, nv);
alpar@1:       for (k = 1; k <= na; k++)
alpar@1:       {  i = glp_sdf_read_int(data);
alpar@1:          if (!(1 <= i && i <= nv))
alpar@1:             glp_sdf_error(data, "tail vertex number out of range\n");
alpar@1:          j = glp_sdf_read_int(data);
alpar@1:          if (!(1 <= j && j <= nv))
alpar@1:             glp_sdf_error(data, "head vertex number out of range\n");
alpar@1:          glp_add_arc(G, i, j);
alpar@1:       }
alpar@1:       xprintf("%d lines were read\n", glp_sdf_line(data));
alpar@1:       ret = 0;
alpar@1: done: if (data != NULL) glp_sdf_close_file(data);
alpar@1:       return ret;
alpar@1: }
alpar@1: 
alpar@1: /***********************************************************************
alpar@1: *  NAME
alpar@1: *
alpar@1: *  glp_write_graph - write graph to plain text file
alpar@1: *
alpar@1: *  SYNOPSIS
alpar@1: *
alpar@1: *  int glp_write_graph(glp_graph *G, const char *fname).
alpar@1: *
alpar@1: *  DESCRIPTION
alpar@1: *
alpar@1: *  The routine glp_write_graph writes the specified graph to a plain
alpar@1: *  text file.
alpar@1: *
alpar@1: *  RETURNS
alpar@1: *
alpar@1: *  If the operation was successful, the routine returns zero. Otherwise
alpar@1: *  it prints an error message and returns non-zero. */
alpar@1: 
alpar@1: int glp_write_graph(glp_graph *G, const char *fname)
alpar@1: {     XFILE *fp;
alpar@1:       glp_vertex *v;
alpar@1:       glp_arc *a;
alpar@1:       int i, count, ret;
alpar@1:       xprintf("Writing graph to `%s'...\n", fname);
alpar@1:       fp = xfopen(fname, "w"), count = 0;
alpar@1:       if (fp == NULL)
alpar@1:       {  xprintf("Unable to create `%s' - %s\n", fname, xerrmsg());
alpar@1:          ret = 1;
alpar@1:          goto done;
alpar@1:       }
alpar@1:       xfprintf(fp, "%d %d\n", G->nv, G->na), count++;
alpar@1:       for (i = 1; i <= G->nv; i++)
alpar@1:       {  v = G->v[i];
alpar@1:          for (a = v->out; a != NULL; a = a->t_next)
alpar@1:             xfprintf(fp, "%d %d\n", a->tail->i, a->head->i), count++;
alpar@1:       }
alpar@1:       xfflush(fp);
alpar@1:       if (xferror(fp))
alpar@1:       {  xprintf("Write error on `%s' - %s\n", fname, xerrmsg());
alpar@1:          ret = 1;
alpar@1:          goto done;
alpar@1:       }
alpar@1:       xprintf("%d lines were written\n", count);
alpar@1:       ret = 0;
alpar@1: done: if (fp != NULL) xfclose(fp);
alpar@1:       return ret;
alpar@1: }
alpar@1: 
alpar@1: /* eof */