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/* rdcnf.c (read CNF-SAT problem data in DIMACS format) */
/***********************************************************************
* This code is part of GLPK (GNU Linear Programming Kit).
* Copyright (C) 2010-2016 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 "dimacs.h"
#include "misc.h"
#include "prob.h"
#define xfprintf glp_format
#define error dmx_error
#define warning dmx_warning
#define read_char dmx_read_char
#define read_designator dmx_read_designator
#define read_field dmx_read_field
#define end_of_line dmx_end_of_line
#define check_int dmx_check_int
int glp_read_cnfsat(glp_prob *P, const char *fname)
{ /* read CNF-SAT problem data in DIMACS format */
DMX _csa, *csa = &_csa;
int m, n, i, j, len, neg, rhs, ret = 0, *ind = NULL;
double *val = NULL;
char *map = NULL;
#if 0 /* 04/IV-2016 */
if (P == NULL || P->magic != GLP_PROB_MAGIC)
xerror("glp_read_cnfsat: P = %p; invalid problem object\n",
P);
#endif
if (fname == NULL)
xerror("glp_read_cnfsat: fname = %p; invalid parameter\n",
fname);
glp_erase_prob(P);
if (setjmp(csa->jump))
{ ret = 1;
goto done;
}
csa->fname = fname;
csa->fp = NULL;
csa->count = 0;
csa->c = '\n';
csa->field[0] = '\0';
csa->empty = csa->nonint = 0;
xprintf("Reading CNF-SAT problem data from '%s'...\n", fname);
csa->fp = glp_open(fname, "r");
if (csa->fp == NULL)
{ xprintf("Unable to open '%s' - %s\n", fname, get_err_msg());
longjmp(csa->jump, 1);
}
/* read problem line */
read_designator(csa);
if (strcmp(csa->field, "p") != 0)
error(csa, "problem line missing or invalid");
read_field(csa);
if (strcmp(csa->field, "cnf") != 0)
error(csa, "wrong problem designator; 'cnf' expected\n");
read_field(csa);
if (!(str2int(csa->field, &n) == 0 && n >= 0))
error(csa, "number of variables missing or invalid\n");
read_field(csa);
if (!(str2int(csa->field, &m) == 0 && m >= 0))
error(csa, "number of clauses missing or invalid\n");
xprintf("Instance has %d variable%s and %d clause%s\n",
n, n == 1 ? "" : "s", m, m == 1 ? "" : "s");
end_of_line(csa);
if (m > 0)
glp_add_rows(P, m);
if (n > 0)
{ glp_add_cols(P, n);
for (j = 1; j <= n; j++)
glp_set_col_kind(P, j, GLP_BV);
}
/* allocate working arrays */
ind = xcalloc(1+n, sizeof(int));
val = xcalloc(1+n, sizeof(double));
map = xcalloc(1+n, sizeof(char));
for (j = 1; j <= n; j++) map[j] = 0;
/* read clauses */
for (i = 1; i <= m; i++)
{ /* read i-th clause */
len = 0, rhs = 1;
for (;;)
{ /* skip white-space characters */
while (csa->c == ' ' || csa->c == '\n')
read_char(csa);
/* read term */
read_field(csa);
if (str2int(csa->field, &j) != 0)
error(csa, "variable number missing or invalid\n");
if (j > 0)
neg = 0;
else if (j < 0)
neg = 1, j = -j, rhs--;
else
break;
if (!(1 <= j && j <= n))
error(csa, "variable number out of range\n");
if (map[j])
error(csa, "duplicate variable number\n");
len++, ind[len] = j, val[len] = (neg ? -1.0 : +1.0);
map[j] = 1;
}
glp_set_row_bnds(P, i, GLP_LO, (double)rhs, 0.0);
glp_set_mat_row(P, i, len, ind, val);
while (len > 0) map[ind[len--]] = 0;
}
xprintf("%d lines were read\n", csa->count);
/* problem data has been successfully read */
glp_sort_matrix(P);
done: if (csa->fp != NULL) glp_close(csa->fp);
if (ind != NULL) xfree(ind);
if (val != NULL) xfree(val);
if (map != NULL) xfree(map);
if (ret) glp_erase_prob(P);
return ret;
}
/* eof */
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