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133 lines
4.5 KiB
133 lines
4.5 KiB
/* glpapi19.c (driver to MiniSat solver) */
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/***********************************************************************
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* This code is part of GLPK (GNU Linear Programming Kit).
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*
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* Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
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* 2009, 2010, 2011, 2013 Andrew Makhorin, Department for Applied
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* Informatics, Moscow Aviation Institute, Moscow, Russia. All rights
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* reserved. E-mail: <mao@gnu.org>.
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*
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* GLPK is free software: you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* GLPK is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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* License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with GLPK. If not, see <http://www.gnu.org/licenses/>.
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***********************************************************************/
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#include "env.h"
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#include "minisat.h"
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#include "prob.h"
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int glp_minisat1(glp_prob *P)
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{ /* solve CNF-SAT problem with MiniSat solver */
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solver *s;
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GLPAIJ *aij;
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int i, j, len, ret, *ind;
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double sum;
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/* check problem object */
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if (P == NULL || P->magic != GLP_PROB_MAGIC)
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xerror("glp_minisat1: P = %p; invalid problem object\n",
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P);
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if (P->tree != NULL)
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xerror("glp_minisat1: operation not allowed\n");
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/* integer solution is currently undefined */
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P->mip_stat = GLP_UNDEF;
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P->mip_obj = 0.0;
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/* check that problem object encodes CNF-SAT instance */
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if (glp_check_cnfsat(P) != 0)
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{ xprintf("glp_minisat1: problem object does not encode CNF-SAT "
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"instance\n");
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ret = GLP_EDATA;
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goto done;
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}
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/* solve CNF-SAT problem */
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xprintf("Solving CNF-SAT problem...\n");
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xprintf("Instance has %d variable%s, %d clause%s, and %d literal%"
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"s\n", P->n, P->n == 1 ? "" : "s", P->m, P->m == 1 ? "" : "s",
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P->nnz, P->nnz == 1 ? "" : "s");
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/* if CNF-SAT has no clauses, it is satisfiable */
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if (P->m == 0)
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{ P->mip_stat = GLP_OPT;
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for (j = 1; j <= P->n; j++)
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P->col[j]->mipx = 0.0;
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goto fini;
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}
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/* if CNF-SAT has an empty clause, it is unsatisfiable */
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for (i = 1; i <= P->m; i++)
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{ if (P->row[i]->ptr == NULL)
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{ P->mip_stat = GLP_NOFEAS;
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goto fini;
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}
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}
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/* prepare input data for the solver */
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s = solver_new();
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solver_setnvars(s, P->n);
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ind = xcalloc(1+P->n, sizeof(int));
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for (i = 1; i <= P->m; i++)
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{ len = 0;
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for (aij = P->row[i]->ptr; aij != NULL; aij = aij->r_next)
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{ ind[++len] = toLit(aij->col->j-1);
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if (aij->val < 0.0)
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ind[len] = lit_neg(ind[len]);
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}
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xassert(len > 0);
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xassert(solver_addclause(s, &ind[1], &ind[1+len]));
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}
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xfree(ind);
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/* call the solver */
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s->verbosity = 1;
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if (solver_solve(s, 0, 0))
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{ /* instance is reported as satisfiable */
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P->mip_stat = GLP_OPT;
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/* copy solution to the problem object */
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xassert(s->model.size == P->n);
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for (j = 1; j <= P->n; j++)
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{ P->col[j]->mipx =
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s->model.ptr[j-1] == l_True ? 1.0 : 0.0;
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}
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/* compute row values */
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for (i = 1; i <= P->m; i++)
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{ sum = 0;
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for (aij = P->row[i]->ptr; aij != NULL; aij = aij->r_next)
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sum += aij->val * aij->col->mipx;
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P->row[i]->mipx = sum;
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}
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/* check integer feasibility */
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for (i = 1; i <= P->m; i++)
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{ if (P->row[i]->mipx < P->row[i]->lb)
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{ /* solution is wrong */
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P->mip_stat = GLP_UNDEF;
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break;
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}
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}
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}
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else
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{ /* instance is reported as unsatisfiable */
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P->mip_stat = GLP_NOFEAS;
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}
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solver_delete(s);
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fini: /* report the instance status */
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if (P->mip_stat == GLP_OPT)
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{ xprintf("SATISFIABLE\n");
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ret = 0;
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}
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else if (P->mip_stat == GLP_NOFEAS)
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{ xprintf("UNSATISFIABLE\n");
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ret = 0;
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}
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else
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{ xprintf("glp_minisat1: solver failed\n");
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ret = GLP_EFAIL;
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}
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done: return ret;
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}
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/* eof */
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