lemon-project-template-glpk
view deps/glpk/src/glpapi18.c @ 9:33de93886c88
Import GLPK 4.47
| author | Alpar Juttner <alpar@cs.elte.hu> |
|---|---|
| date | Sun, 06 Nov 2011 20:59:10 +0100 |
| parents | |
| children |
line source
1 /* glpapi18.c (maximum clique problem) */
3 /***********************************************************************
4 * This code is part of GLPK (GNU Linear Programming Kit).
5 *
6 * Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
7 * 2009, 2010, 2011 Andrew Makhorin, Department for Applied Informatics,
8 * Moscow Aviation Institute, Moscow, Russia. All rights reserved.
9 * E-mail: <mao@gnu.org>.
10 *
11 * GLPK is free software: you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by
13 * the Free Software Foundation, either version 3 of the License, or
14 * (at your option) any later version.
15 *
16 * GLPK is distributed in the hope that it will be useful, but WITHOUT
17 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
18 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
19 * License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with GLPK. If not, see <http://www.gnu.org/licenses/>.
23 ***********************************************************************/
25 #include "glpapi.h"
26 #include "glpnet.h"
28 static void set_edge(int nv, unsigned char a[], int i, int j)
29 { int k;
30 xassert(1 <= j && j < i && i <= nv);
31 k = ((i - 1) * (i - 2)) / 2 + (j - 1);
32 a[k / CHAR_BIT] |=
33 (unsigned char)(1 << ((CHAR_BIT - 1) - k % CHAR_BIT));
34 return;
35 }
37 int glp_wclique_exact(glp_graph *G, int v_wgt, double *sol, int v_set)
38 { /* find maximum weight clique with exact algorithm */
39 glp_arc *e;
40 int i, j, k, len, x, *w, *ind, ret = 0;
41 unsigned char *a;
42 double s, t;
43 if (v_wgt >= 0 && v_wgt > G->v_size - (int)sizeof(double))
44 xerror("glp_wclique_exact: v_wgt = %d; invalid parameter\n",
45 v_wgt);
46 if (v_set >= 0 && v_set > G->v_size - (int)sizeof(int))
47 xerror("glp_wclique_exact: v_set = %d; invalid parameter\n",
48 v_set);
49 if (G->nv == 0)
50 { /* empty graph has only empty clique */
51 if (sol != NULL) *sol = 0.0;
52 return 0;
53 }
54 /* allocate working arrays */
55 w = xcalloc(1+G->nv, sizeof(int));
56 ind = xcalloc(1+G->nv, sizeof(int));
57 len = G->nv; /* # vertices */
58 len = len * (len - 1) / 2; /* # entries in lower triangle */
59 len = (len + (CHAR_BIT - 1)) / CHAR_BIT; /* # bytes needed */
60 a = xcalloc(len, sizeof(char));
61 memset(a, 0, len * sizeof(char));
62 /* determine vertex weights */
63 s = 0.0;
64 for (i = 1; i <= G->nv; i++)
65 { if (v_wgt >= 0)
66 { memcpy(&t, (char *)G->v[i]->data + v_wgt, sizeof(double));
67 if (!(0.0 <= t && t <= (double)INT_MAX && t == floor(t)))
68 { ret = GLP_EDATA;
69 goto done;
70 }
71 w[i] = (int)t;
72 }
73 else
74 w[i] = 1;
75 s += (double)w[i];
76 }
77 if (s > (double)INT_MAX)
78 { ret = GLP_EDATA;
79 goto done;
80 }
81 /* build the adjacency matrix */
82 for (i = 1; i <= G->nv; i++)
83 { for (e = G->v[i]->in; e != NULL; e = e->h_next)
84 { j = e->tail->i;
85 /* there exists edge (j,i) in the graph */
86 if (i > j) set_edge(G->nv, a, i, j);
87 }
88 for (e = G->v[i]->out; e != NULL; e = e->t_next)
89 { j = e->head->i;
90 /* there exists edge (i,j) in the graph */
91 if (i > j) set_edge(G->nv, a, i, j);
92 }
93 }
94 /* find maximum weight clique in the graph */
95 len = wclique(G->nv, w, a, ind);
96 /* compute the clique weight */
97 s = 0.0;
98 for (k = 1; k <= len; k++)
99 { i = ind[k];
100 xassert(1 <= i && i <= G->nv);
101 s += (double)w[i];
102 }
103 if (sol != NULL) *sol = s;
104 /* mark vertices included in the clique */
105 if (v_set >= 0)
106 { x = 0;
107 for (i = 1; i <= G->nv; i++)
108 memcpy((char *)G->v[i]->data + v_set, &x, sizeof(int));
109 x = 1;
110 for (k = 1; k <= len; k++)
111 { i = ind[k];
112 memcpy((char *)G->v[i]->data + v_set, &x, sizeof(int));
113 }
114 }
115 done: /* free working arrays */
116 xfree(w);
117 xfree(ind);
118 xfree(a);
119 return ret;
120 }
122 /* eof */