/* helper function for command flags */
int handle_need_input(void)
{
int status;
igraph_bool_t isdag;
normal("Configuring input\n");
if(infname)
{
info("Using %s as input file\n",infname);
infile = fopen(infname,"r");
if(!infile)
{
warning("failed to open file %s for graph input, using stdin instead\n",infname);
infile = stdin;
infname = NULL;
}
}
else
infile = stdin;
status = ggen_read_graph(&g,infile);
if(infname)
fclose(infile);
if(status)
{
error("Failed to read graph\n");
return 1;
}
/* check that the graph is a DAG */
status = igraph_is_dag(&g,&isdag);
if(status || !isdag)
{
error("Input graph failed DAG verification\n");
return 1;
}
normal("Input configured and graph read\n");
return 0;
}
int main() {
igraph_t g;
igraph_vector_t weights, result;
igraph_bool_t dag;
int retval;
igraph_vector_init(&result, 0);
igraph_set_error_handler(&igraph_error_handler_printignore);
/***********************************************************************/
/* Exact solution with integer programming */
/***********************************************************************/
/* Simple unweighted graph */
igraph_small(&g, 0, IGRAPH_DIRECTED, 0,1, 1,2, 2,0, 2,3, 2,4, 0,4, 4,3, 5,0, 6,5, -1);
retval = igraph_feedback_arc_set(&g, &result, 0, IGRAPH_FAS_EXACT_IP);
if (retval == IGRAPH_UNIMPLEMENTED)
return 77;
igraph_vector_print(&result);
igraph_delete_edges(&g, igraph_ess_vector(&result));
igraph_is_dag(&g, &dag);
if (!dag)
return 1;
igraph_destroy(&g);
/* Simple weighted graph */
igraph_small(&g, 0, IGRAPH_DIRECTED, 0,1, 1,2, 2,0, 2,3, 2,4, 0,4, 4,3, 5,0, 6,5, -1);
igraph_vector_init_int_end(&weights, -1, 1, 1, 3, 1, 1, 1, 1, 1, 1, -1);
igraph_feedback_arc_set(&g, &result, &weights, IGRAPH_FAS_EXACT_IP);
igraph_vector_print(&result);
igraph_delete_edges(&g, igraph_ess_vector(&result));
igraph_is_dag(&g, &dag);
if (!dag)
return 2;
igraph_vector_destroy(&weights);
igraph_destroy(&g);
/* Simple unweighted graph with loops */
igraph_small(&g, 0, IGRAPH_DIRECTED, 0,1, 1,2, 2,0, 2,3, 2,4, 0,4, 4,3, 5,0, 6,5, 1,1, 4,4, -1);
igraph_feedback_arc_set(&g, &result, 0, IGRAPH_FAS_EXACT_IP);
igraph_vector_print(&result);
igraph_delete_edges(&g, igraph_ess_vector(&result));
igraph_is_dag(&g, &dag);
if (!dag)
return 3;
igraph_destroy(&g);
/* Disjoint union of two almost identical graphs */
igraph_small(&g, 0, IGRAPH_DIRECTED,
0,1, 1,2, 2,0, 2,3, 2,4, 0,4, 4,3, 5,0, 6,5, 1,1, 4,4,
7,8, 8,9, 9,7, 9,10, 9,11, 7,11, 11,10, 12,7, 13,12,
-1);
igraph_feedback_arc_set(&g, &result, 0, IGRAPH_FAS_EXACT_IP);
igraph_vector_print(&result);
igraph_delete_edges(&g, igraph_ess_vector(&result));
igraph_is_dag(&g, &dag);
if (!dag)
return 4;
igraph_destroy(&g);
/* Graph with lots of isolated vertices */
igraph_small(&g, 10000, IGRAPH_DIRECTED, 0,1, -1);
igraph_feedback_arc_set(&g, &result, 0, IGRAPH_FAS_EXACT_IP);
igraph_vector_print(&result);
igraph_delete_edges(&g, igraph_ess_vector(&result));
igraph_is_dag(&g, &dag);
if (!dag)
return 5;
igraph_destroy(&g);
igraph_vector_destroy(&result);
return 0;
}
