diff options
Diffstat (limited to 'glpk-5.0/src/api/strong.c')
| -rw-r--r-- | glpk-5.0/src/api/strong.c | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/glpk-5.0/src/api/strong.c b/glpk-5.0/src/api/strong.c new file mode 100644 index 0000000..8921f5e --- /dev/null +++ b/glpk-5.0/src/api/strong.c @@ -0,0 +1,108 @@ +/* strong.c (find all strongly connected components of graph) */ + +/*********************************************************************** +* This code is part of GLPK (GNU Linear Programming Kit). +* Copyright (C) 2009-2016 Free Software Foundation, Inc. +* Written by Andrew Makhorin <mao@gnu.org>. +* +* GLPK is free software: you can redistribute it and/or modify it +* under the terms of the GNU General Public License as published by +* the Free Software Foundation, either version 3 of the License, or +* (at your option) any later version. +* +* GLPK is distributed in the hope that it will be useful, but WITHOUT +* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY +* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public +* License for more details. +* +* You should have received a copy of the GNU General Public License +* along with GLPK. If not, see <http://www.gnu.org/licenses/>. +***********************************************************************/ + +#include "env.h" +#include "glpk.h" +#include "mc13d.h" + +/*********************************************************************** +* NAME +* +* glp_strong_comp - find all strongly connected components of graph +* +* SYNOPSIS +* +* int glp_strong_comp(glp_graph *G, int v_num); +* +* DESCRIPTION +* +* The routine glp_strong_comp finds all strongly connected components +* of the specified graph. +* +* The parameter v_num specifies an offset of the field of type int +* in the vertex data block, to which the routine stores the number of +* a strongly connected component containing that vertex. If v_num < 0, +* no component numbers are stored. +* +* The components are numbered in arbitrary order from 1 to nc, where +* nc is the total number of components found, 0 <= nc <= |V|. However, +* the component numbering has the property that for every arc (i->j) +* in the graph the condition num(i) >= num(j) holds. +* +* RETURNS +* +* The routine returns nc, the total number of components found. */ + +int glp_strong_comp(glp_graph *G, int v_num) +{ glp_vertex *v; + glp_arc *a; + int i, k, last, n, na, nc, *icn, *ip, *lenr, *ior, *ib, *lowl, + *numb, *prev; + if (v_num >= 0 && v_num > G->v_size - (int)sizeof(int)) + xerror("glp_strong_comp: v_num = %d; invalid offset\n", + v_num); + n = G->nv; + if (n == 0) + { nc = 0; + goto done; + } + na = G->na; + icn = xcalloc(1+na, sizeof(int)); + ip = xcalloc(1+n, sizeof(int)); + lenr = xcalloc(1+n, sizeof(int)); + ior = xcalloc(1+n, sizeof(int)); + ib = xcalloc(1+n, sizeof(int)); + lowl = xcalloc(1+n, sizeof(int)); + numb = xcalloc(1+n, sizeof(int)); + prev = xcalloc(1+n, sizeof(int)); + k = 1; + for (i = 1; i <= n; i++) + { v = G->v[i]; + ip[i] = k; + for (a = v->out; a != NULL; a = a->t_next) + icn[k++] = a->head->i; + lenr[i] = k - ip[i]; + } + xassert(na == k-1); + nc = mc13d(n, icn, ip, lenr, ior, ib, lowl, numb, prev); + if (v_num >= 0) + { xassert(ib[1] == 1); + for (k = 1; k <= nc; k++) + { last = (k < nc ? ib[k+1] : n+1); + xassert(ib[k] < last); + for (i = ib[k]; i < last; i++) + { v = G->v[ior[i]]; + memcpy((char *)v->data + v_num, &k, sizeof(int)); + } + } + } + xfree(icn); + xfree(ip); + xfree(lenr); + xfree(ior); + xfree(ib); + xfree(lowl); + xfree(numb); + xfree(prev); +done: return nc; +} + +/* eof */ |