Edit: /usr/include/boost/graph/stoer_wagner_min_cut.hpp (12415B)
// Copyright Daniel Trebbien 2010.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or the copy at
// http://www.boost.org/LICENSE_1_0.txt)
#ifndef BOOST_GRAPH_STOER_WAGNER_MIN_CUT_HPP
#define BOOST_GRAPH_STOER_WAGNER_MIN_CUT_HPP 1
#include
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namespace boost
{
namespace detail
{
template < typename ParityMap, typename WeightMap, typename IndexMap >
class mas_min_cut_visitor : public boost::default_mas_visitor
{
typedef one_bit_color_map< IndexMap > InternalParityMap;
typedef typename boost::property_traits< WeightMap >::value_type
weight_type;
public:
template < typename Graph >
mas_min_cut_visitor(const Graph& g, ParityMap parity,
weight_type& cutweight, const WeightMap& weight_map,
IndexMap index_map)
: m_bestParity(parity)
, m_parity(make_one_bit_color_map(num_vertices(g), index_map))
, m_bestWeight(cutweight)
, m_cutweight(0)
, m_visited(0)
, m_weightMap(weight_map)
{
// set here since the init list sets the reference
m_bestWeight = (std::numeric_limits< weight_type >::max)();
}
template < typename Vertex, typename Graph >
void initialize_vertex(Vertex u, const Graph& g)
{
typedef typename boost::property_traits< ParityMap >::value_type
parity_type;
typedef
typename boost::property_traits< InternalParityMap >::value_type
internal_parity_type;
put(m_parity, u, internal_parity_type(0));
put(m_bestParity, u, parity_type(0));
}
template < typename Edge, typename Graph >
void examine_edge(Edge e, const Graph& g)
{
weight_type w = get(m_weightMap, e);
// if the target of e is already marked then decrease cutweight
// otherwise, increase it
if (get(m_parity, boost::target(e, g)))
{
m_cutweight -= w;
}
else
{
m_cutweight += w;
}
}
template < typename Vertex, typename Graph >
void finish_vertex(Vertex u, const Graph& g)
{
typedef
typename boost::property_traits< InternalParityMap >::value_type
internal_parity_type;
++m_visited;
put(m_parity, u, internal_parity_type(1));
if (m_cutweight < m_bestWeight && m_visited < num_vertices(g))
{
m_bestWeight = m_cutweight;
BGL_FORALL_VERTICES_T(i, g, Graph)
{
put(m_bestParity, i, get(m_parity, i));
}
}
}
inline void clear()
{
m_bestWeight = (std::numeric_limits< weight_type >::max)();
m_visited = 0;
m_cutweight = 0;
}
private:
ParityMap m_bestParity;
InternalParityMap m_parity;
weight_type& m_bestWeight;
weight_type m_cutweight;
unsigned m_visited;
const WeightMap& m_weightMap;
};
/**
* \brief Computes a min-cut of the input graph
*
* Computes a min-cut of the input graph using the Stoer-Wagner algorithm.
*
* \pre \p g is a connected, undirected graph
* \pre pq.empty()
* \param[in] g the input graph
* \param[in] weights a readable property map from each edge to its weight
* (a non-negative value) \param[out] parities a writable property map from
* each vertex to a bool type object for distinguishing the two vertex sets
* of the min-cut \param[out] assignments a read/write property map from
* each vertex to a \c vertex_descriptor object. This map serves as work
* space, and no particular meaning should be derived from property values
* after completion of the algorithm.
* \param[out] pq a keyed, updatable max-priority queue
* \returns the cut weight of the min-cut
* \see
* http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.114.6687&rep=rep1&type=pdf
* \see
* http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.31.614&rep=rep1&type=pdf
*
* \author Daniel Trebbien
* \date 2010-09-11
*/
template < class UndirectedGraph, class WeightMap, class ParityMap,
class VertexAssignmentMap, class KeyedUpdatablePriorityQueue,
class IndexMap >
typename boost::property_traits< WeightMap >::value_type
stoer_wagner_min_cut(const UndirectedGraph& g, WeightMap weights,
ParityMap parities, VertexAssignmentMap assignments,
KeyedUpdatablePriorityQueue& pq, IndexMap index_map)
{
typedef
typename boost::graph_traits< UndirectedGraph >::vertex_descriptor
vertex_descriptor;
typedef typename boost::property_traits< WeightMap >::value_type
weight_type;
typename graph_traits< UndirectedGraph >::vertex_iterator u_iter, u_end;
weight_type bestW = (std::numeric_limits< weight_type >::max)();
weight_type bestThisTime = (std::numeric_limits< weight_type >::max)();
vertex_descriptor bestStart
= boost::graph_traits< UndirectedGraph >::null_vertex();
detail::mas_min_cut_visitor< ParityMap, WeightMap, IndexMap > vis(
g, parities, bestThisTime, weights, index_map);
// for each node in the graph,
for (boost::tie(u_iter, u_end) = vertices(g); u_iter != u_end; ++u_iter)
{
// run the MAS and find the min cut
vis.clear();
boost::maximum_adjacency_search(g,
boost::weight_map(weights)
.visitor(vis)
.root_vertex(*u_iter)
.vertex_assignment_map(assignments)
.max_priority_queue(pq));
if (bestThisTime < bestW)
{
bestW = bestThisTime;
bestStart = *u_iter;
}
}
// Run one more time, starting from the best start location, to
// ensure the visitor has the best values.
vis.clear();
boost::maximum_adjacency_search(g,
boost::vertex_assignment_map(assignments)
.weight_map(weights)
.visitor(vis)
.root_vertex(bestStart)
.max_priority_queue(pq));
return bestW;
}
} // end `namespace detail` within `namespace boost`
template < class UndirectedGraph, class WeightMap, class ParityMap,
class VertexAssignmentMap, class KeyedUpdatablePriorityQueue,
class IndexMap >
typename boost::property_traits< WeightMap >::value_type stoer_wagner_min_cut(
const UndirectedGraph& g, WeightMap weights, ParityMap parities,
VertexAssignmentMap assignments, KeyedUpdatablePriorityQueue& pq,
IndexMap index_map)
{
BOOST_CONCEPT_ASSERT((boost::IncidenceGraphConcept< UndirectedGraph >));
BOOST_CONCEPT_ASSERT((boost::VertexListGraphConcept< UndirectedGraph >));
typedef typename boost::graph_traits< UndirectedGraph >::vertex_descriptor
vertex_descriptor;
typedef typename boost::graph_traits< UndirectedGraph >::vertices_size_type
vertices_size_type;
typedef typename boost::graph_traits< UndirectedGraph >::edge_descriptor
edge_descriptor;
BOOST_CONCEPT_ASSERT((boost::Convertible<
typename boost::graph_traits< UndirectedGraph >::directed_category,
boost::undirected_tag >));
BOOST_CONCEPT_ASSERT(
(boost::ReadablePropertyMapConcept< WeightMap, edge_descriptor >));
// typedef typename boost::property_traits::value_type
// weight_type;
BOOST_CONCEPT_ASSERT(
(boost::WritablePropertyMapConcept< ParityMap, vertex_descriptor >));
// typedef typename boost::property_traits::value_type
// parity_type;
BOOST_CONCEPT_ASSERT(
(boost::ReadWritePropertyMapConcept< VertexAssignmentMap,
vertex_descriptor >));
BOOST_CONCEPT_ASSERT((boost::Convertible< vertex_descriptor,
typename boost::property_traits< VertexAssignmentMap >::value_type >));
BOOST_CONCEPT_ASSERT(
(boost::KeyedUpdatableQueueConcept< KeyedUpdatablePriorityQueue >));
vertices_size_type n = num_vertices(g);
if (n < 2)
throw boost::bad_graph(
"the input graph must have at least two vertices.");
else if (!pq.empty())
throw std::invalid_argument(
"the max-priority queue must be empty initially.");
return detail::stoer_wagner_min_cut(
g, weights, parities, assignments, pq, index_map);
}
namespace graph
{
namespace detail
{
template < class UndirectedGraph, class WeightMap >
struct stoer_wagner_min_cut_impl
{
typedef typename boost::property_traits< WeightMap >::value_type
result_type;
template < typename ArgPack >
result_type operator()(const UndirectedGraph& g, WeightMap weights,
const ArgPack& arg_pack) const
{
using namespace boost::graph::keywords;
typedef typename boost::graph_traits<
UndirectedGraph >::vertex_descriptor vertex_descriptor;
typedef typename boost::property_traits< WeightMap >::value_type
weight_type;
typedef boost::detail::make_priority_queue_from_arg_pack_gen<
boost::graph::keywords::tag::max_priority_queue,
weight_type, vertex_descriptor,
std::greater< weight_type > >
gen_type;
gen_type gen(
choose_param(get_param(arg_pack, boost::distance_zero_t()),
weight_type(0)));
typename boost::result_of< gen_type(
const UndirectedGraph&, const ArgPack&) >::type pq
= gen(g, arg_pack);
boost::dummy_property_map dummy_prop;
return boost::stoer_wagner_min_cut(g, weights,
arg_pack[_parity_map | dummy_prop],
boost::detail::make_property_map_from_arg_pack_gen<
tag::vertex_assignment_map, vertex_descriptor >(
vertex_descriptor())(g, arg_pack),
pq,
boost::detail::override_const_property(
arg_pack, _vertex_index_map, g, vertex_index));
}
};
}
BOOST_GRAPH_MAKE_FORWARDING_FUNCTION(stoer_wagner_min_cut, 2, 4)
}
// Named parameter interface
BOOST_GRAPH_MAKE_OLD_STYLE_PARAMETER_FUNCTION(stoer_wagner_min_cut, 2)
namespace graph
{
// version without IndexMap kept for backwards compatibility
// (but requires vertex_index_t to be defined in the graph)
// Place after the macro to avoid compilation errors
template < class UndirectedGraph, class WeightMap, class ParityMap,
class VertexAssignmentMap, class KeyedUpdatablePriorityQueue >
typename boost::property_traits< WeightMap >::value_type
stoer_wagner_min_cut(const UndirectedGraph& g, WeightMap weights,
ParityMap parities, VertexAssignmentMap assignments,
KeyedUpdatablePriorityQueue& pq)
{
return stoer_wagner_min_cut(
g, weights, parities, assignments, pq, get(vertex_index, g));
}
} // end `namespace graph`
} // end `namespace boost`
#include
#endif // !BOOST_GRAPH_STOER_WAGNER_MIN_CUT_HPP