Edit: /usr/include/boost/graph/read_dimacs.hpp (12080B)
//=======================================================================
// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
// Authors: Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//=======================================================================
/*
Reads maximal flow problem in extended DIMACS format.
This works, but could use some polishing.
*/
/* ----------------------------------------------------------------- */
#ifndef BOOST_GRAPH_READ_DIMACS_HPP
#define BOOST_GRAPH_READ_DIMACS_HPP
#include
#include
#include
#include
#include
#include
#include
namespace boost
{
namespace detail
{
template < class Graph, class CapacityMap, class ReverseEdgeMap >
int read_dimacs_max_flow_internal(Graph& g, CapacityMap capacity,
ReverseEdgeMap reverse_edge,
typename graph_traits< Graph >::vertex_descriptor& src,
typename graph_traits< Graph >::vertex_descriptor& sink,
std::istream& in, bool require_source_and_sink,
const std::string& problem_type)
{
// const int MAXLINE = 100; /* max line length in the input file
// */
const int ARC_FIELDS = 3; /* no of fields in arc line */
const int NODE_FIELDS = 2; /* no of fields in node line */
const int P_FIELDS = 3; /* no of fields in problem line */
typedef
typename graph_traits< Graph >::vertex_descriptor vertex_descriptor;
typedef typename graph_traits< Graph >::edge_descriptor edge_descriptor;
std::vector< vertex_descriptor > verts;
long m, n, /* number of edges and nodes */
i, head, tail, cap;
long no_lines = 0, /* no of current input line */
no_plines = 0, /* no of problem-lines */
no_nslines = 0, /* no of node-source-lines */
no_nklines = 0, /* no of node-source-lines */
no_alines = 0; /* no of arc-lines */
std::string in_line; /* for reading input line */
char pr_type[4]; /* for reading type of the problem */
char nd; /* source (s) or sink (t) */
int k, /* temporary */
err_no; /* no of detected error */
/* -------------- error numbers & error messages ---------------- */
const int EN1 = 0;
const int EN2 = 1;
const int EN3 = 2;
const int EN4 = 3;
// const int EN6 = 4;
// const int EN10 = 5;
// const int EN7 = 6;
const int EN8 = 7;
const int EN9 = 8;
const int EN11 = 9;
const int EN12 = 10;
// const int EN13 = 11;
const int EN14 = 12;
const int EN16 = 13;
const int EN15 = 14;
const int EN17 = 15;
const int EN18 = 16;
const int EN21 = 17;
const int EN19 = 18;
const int EN20 = 19;
const int EN22 = 20;
static const char* err_message[] = {
/* 0*/ "more than one problem line.",
/* 1*/ "wrong number of parameters in the problem line.",
/* 2*/ "it is not a Max Flow problem line.",
/* 3*/ "bad value of a parameter in the problem line.",
/* 4*/ "can't obtain enough memory to solve this problem.",
/* 5*/ "more than one line with the problem name.",
/* 6*/ "can't read problem name.",
/* 7*/ "problem description must be before node description.",
/* 8*/ "this parser doesn't support multiply sources and sinks.",
/* 9*/ "wrong number of parameters in the node line.",
/*10*/ "wrong value of parameters in the node line.",
/*11*/ " ",
/*12*/
"source and sink descriptions must be before arc descriptions.",
/*13*/ "too many arcs in the input.",
/*14*/ "wrong number of parameters in the arc line.",
/*15*/ "wrong value of parameters in the arc line.",
/*16*/ "unknown line type in the input.",
/*17*/ "reading error.",
/*18*/ "not enough arcs in the input.",
/*19*/ "source or sink doesn't have incident arcs.",
/*20*/ "can't read anything from the input file."
};
/* --------------------------------------------------------------- */
/* The main loop:
- reads the line of the input,
- analyses its type,
- checks correctness of parameters,
- puts data to the arrays,
- does service functions
*/
while (std::getline(in, in_line))
{
++no_lines;
switch (in_line[0])
{
case 'c': /* skip lines with comments */
case '\n': /* skip empty lines */
case '\0': /* skip empty lines at the end of file */
break;
case 'p': /* problem description */
if (no_plines > 0)
/* more than one problem line */
{
err_no = EN1;
goto error;
}
no_plines = 1;
if (
/* reading problem line: type of problem, no of nodes, no of
arcs */
std::sscanf(
in_line.c_str(), "%*c %3s %ld %ld", pr_type, &n, &m)
!= P_FIELDS)
/*wrong number of parameters in the problem line*/
{
err_no = EN2;
goto error;
}
if (pr_type != problem_type)
/*wrong problem type*/
{
err_no = EN3;
goto error;
}
if (n <= 0 || m <= 0)
/*wrong value of no of arcs or nodes*/
{
err_no = EN4;
goto error;
}
{
for (long vi = 0; vi < n; ++vi)
verts.push_back(add_vertex(g));
}
break;
case 'n': /* source(s) description */
if (no_plines == 0)
/* there was not problem line above */
{
err_no = EN8;
goto error;
}
/* reading source or sink */
k = std::sscanf(in_line.c_str(), "%*c %ld %c", &i, &nd);
--i; // index from 0
if (k < NODE_FIELDS)
/* node line is incorrect */
{
err_no = EN11;
goto error;
}
if (i < 0 || i > n)
/* wrong value of node */
{
err_no = EN12;
goto error;
}
switch (nd)
{
case 's': /* source line */
if (no_nslines != 0)
/* more than one source line */
{
err_no = EN9;
goto error;
}
no_nslines = 1;
src = verts[i];
break;
case 't': /* sink line */
if (no_nklines != 0)
/* more than one sink line */
{
err_no = EN9;
goto error;
}
no_nklines = 1;
sink = verts[i];
break;
default:
/* wrong type of node-line */
err_no = EN12;
goto error;
}
break;
case 'a': /* arc description */
if (require_source_and_sink
&& (no_nslines == 0 || no_nklines == 0))
/* there was not source and sink description above */
{
err_no = EN14;
goto error;
}
if (no_alines >= m)
/*too many arcs on input*/
{
err_no = EN16;
goto error;
}
if (
/* reading an arc description */
std::sscanf(
in_line.c_str(), "%*c %ld %ld %ld", &tail, &head, &cap)
!= ARC_FIELDS)
/* arc description is not correct */
{
err_no = EN15;
goto error;
}
--tail; // index from 0, not 1
--head;
if (tail < 0 || tail > n || head < 0 || head > n)
/* wrong value of nodes */
{
err_no = EN17;
goto error;
}
{
edge_descriptor e1, e2;
bool in1, in2;
boost::tie(e1, in1) = add_edge(verts[tail], verts[head], g);
boost::tie(e2, in2) = add_edge(verts[head], verts[tail], g);
if (!in1 || !in2)
{
std::cerr << "unable to add edge (" << head << ","
<< tail << ")" << std::endl;
return -1;
}
capacity[e1] = cap;
capacity[e2] = 0;
reverse_edge[e1] = e2;
reverse_edge[e2] = e1;
}
++no_alines;
break;
default:
/* unknown type of line */
err_no = EN18;
goto error;
} /* end of switch */
} /* end of input loop */
/* ----- all is red or error while reading ----- */
if (in.eof() == 0) /* reading error */
{
err_no = EN21;
goto error;
}
if (no_lines == 0) /* empty input */
{
err_no = EN22;
goto error;
}
if (no_alines < m) /* not enough arcs */
{
err_no = EN19;
goto error;
}
if (require_source_and_sink
&& (out_degree(src, g) == 0 || out_degree(sink, g) == 0))
/* no arc goes out of the source */
{
err_no = EN20;
goto error;
}
/* Thanks God! all is done */
return (0);
/* ---------------------------------- */
error: /* error found reading input */
std::printf(
"\nline %ld of input - %s\n", no_lines, err_message[err_no]);
return -1;
}
/* -------------------- end of parser -------------------*/
} // namespace detail
template < class Graph, class CapacityMap, class ReverseEdgeMap >
int read_dimacs_max_flow(Graph& g, CapacityMap capacity,
ReverseEdgeMap reverse_edge,
typename graph_traits< Graph >::vertex_descriptor& src,
typename graph_traits< Graph >::vertex_descriptor& sink,
std::istream& in = std::cin)
{
return detail::read_dimacs_max_flow_internal(
g, capacity, reverse_edge, src, sink, in, true, "max");
}
template < class Graph, class CapacityMap, class ReverseEdgeMap >
int read_dimacs_min_cut(Graph& g, CapacityMap capacity,
ReverseEdgeMap reverse_edge, std::istream& in = std::cin)
{
typename graph_traits< Graph >::vertex_descriptor dummy_src,
dummy_sink; // Not filled in
return detail::read_dimacs_max_flow_internal(
g, capacity, reverse_edge, dummy_src, dummy_sink, in, false, "cut");
}
} // namespace boost
#endif // BOOST_GRAPH_READ_DIMACS_HPP