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/**
*
* Copyright (c) 2010 Matthias Walter (xammy@xammy.homelinux.net)
*
* Authors: Matthias Walter
*
* 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)
*
*/
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/lookup_edge.hpp>
#include <boost/core/lightweight_test.hpp>
#include <boost/graph/bipartite.hpp>
/// Verifies a 2-coloring
template < typename Graph, typename ColorMap >
void check_two_coloring(const Graph& g, const ColorMap color_map)
{
typedef boost::graph_traits< Graph > traits;
typename traits::edge_iterator edge_iter, edge_end;
for (boost::tie(edge_iter, edge_end) = boost::edges(g);
edge_iter != edge_end; ++edge_iter)
{
typename traits::vertex_descriptor source, target;
source = boost::source(*edge_iter, g);
target = boost::target(*edge_iter, g);
BOOST_TEST(
boost::get(color_map, source) != boost::get(color_map, target));
}
}
/// Tests for a vertex sequence to define an odd cycle
template < typename Graph, typename RandomAccessIterator >
void check_odd_cycle(
const Graph& g, RandomAccessIterator first, RandomAccessIterator beyond)
{
typedef boost::graph_traits< Graph > traits;
typename traits::vertex_descriptor first_vertex, current_vertex,
last_vertex;
BOOST_TEST((beyond - first) % 2 == 1);
// std::cout << "odd_cycle: " << int(*first) << std::endl;
for (first_vertex = current_vertex = *first++; first != beyond; ++first)
{
// std::cout << "odd_cycle: " << int(*first) << std::endl;
last_vertex = current_vertex;
current_vertex = *first;
BOOST_TEST(
boost::lookup_edge(current_vertex, last_vertex, g).second);
}
BOOST_TEST(boost::lookup_edge(first_vertex, current_vertex, g).second);
}
/// Call the is_bipartite and find_odd_cycle functions and verify their results.
template < typename Graph, typename IndexMap >
void check_bipartite(const Graph& g, IndexMap index_map, bool is_bipartite)
{
typedef boost::graph_traits< Graph > traits;
typedef std::vector< boost::default_color_type > partition_t;
typedef std::vector< typename traits::vertex_descriptor > vertex_vector_t;
typedef boost::iterator_property_map< partition_t::iterator, IndexMap >
partition_map_t;
partition_t partition(boost::num_vertices(g));
partition_map_t partition_map(partition.begin(), index_map);
vertex_vector_t odd_cycle(boost::num_vertices(g));
bool first_result = boost::is_bipartite(g, index_map, partition_map);
BOOST_TEST(first_result == boost::is_bipartite(g, index_map));
if (first_result)
check_two_coloring(g, partition_map);
BOOST_TEST(first_result == is_bipartite);
typename vertex_vector_t::iterator second_first = odd_cycle.begin();
typename vertex_vector_t::iterator second_beyond
= boost::find_odd_cycle(g, index_map, partition_map, second_first);
if (is_bipartite)
{
BOOST_TEST(second_beyond == second_first);
check_two_coloring(g, partition_map);
}
else
{
check_odd_cycle(g, second_first, second_beyond);
}
second_beyond = boost::find_odd_cycle(g, index_map, second_first);
if (is_bipartite)
{
BOOST_TEST(second_beyond == second_first);
}
else
{
check_odd_cycle(g, second_first, second_beyond);
}
}
int main(int argc, char** argv)
{
typedef boost::adjacency_list< boost::vecS, boost::vecS,
boost::undirectedS >
vector_graph_t;
typedef boost::adjacency_list< boost::listS, boost::listS,
boost::undirectedS >
list_graph_t;
typedef std::pair< int, int > E;
typedef std::map< boost::graph_traits< list_graph_t >::vertex_descriptor,
size_t >
index_map_t;
typedef boost::associative_property_map< index_map_t > index_property_map_t;
/**
* Create the graph drawn below.
*
* 0 - 1 - 2
* | |
* 3 - 4 - 5 - 6
* / \ /
* | 7
* | |
* 8 - 9 - 10
**/
E bipartite_edges[]
= { E(0, 1), E(0, 4), E(1, 2), E(2, 6), E(3, 4), E(3, 8), E(4, 5),
E(4, 7), E(5, 6), E(6, 7), E(7, 10), E(8, 9), E(9, 10) };
vector_graph_t bipartite_vector_graph(&bipartite_edges[0],
&bipartite_edges[0] + sizeof(bipartite_edges) / sizeof(E), 11);
list_graph_t bipartite_list_graph(&bipartite_edges[0],
&bipartite_edges[0] + sizeof(bipartite_edges) / sizeof(E), 11);
/**
* Create the graph drawn below.
*
* 2 - 1 - 0
* | |
* 3 - 6 - 5 - 4
* / \ /
* | 7
* | /
* 8 ---- 9
*
**/
E non_bipartite_edges[] = { E(0, 1), E(0, 4), E(1, 2), E(2, 6), E(3, 4),
E(3, 8), E(4, 5), E(4, 7), E(5, 6), E(6, 7), E(7, 9), E(8, 9) };
vector_graph_t non_bipartite_vector_graph(&non_bipartite_edges[0],
&non_bipartite_edges[0] + sizeof(non_bipartite_edges) / sizeof(E), 10);
list_graph_t non_bipartite_list_graph(&non_bipartite_edges[0],
&non_bipartite_edges[0] + sizeof(non_bipartite_edges) / sizeof(E), 10);
/// Create index maps
index_map_t bipartite_index_map, non_bipartite_index_map;
boost::graph_traits< list_graph_t >::vertex_iterator vertex_iter,
vertex_end;
size_t i = 0;
for (boost::tie(vertex_iter, vertex_end)
= boost::vertices(bipartite_list_graph);
vertex_iter != vertex_end; ++vertex_iter)
{
bipartite_index_map[*vertex_iter] = i++;
}
index_property_map_t bipartite_index_property_map
= index_property_map_t(bipartite_index_map);
i = 0;
for (boost::tie(vertex_iter, vertex_end)
= boost::vertices(non_bipartite_list_graph);
vertex_iter != vertex_end; ++vertex_iter)
{
non_bipartite_index_map[*vertex_iter] = i++;
}
index_property_map_t non_bipartite_index_property_map
= index_property_map_t(non_bipartite_index_map);
/// Call real checks
check_bipartite(bipartite_vector_graph,
boost::get(boost::vertex_index, bipartite_vector_graph), true);
check_bipartite(bipartite_list_graph, bipartite_index_property_map, true);
check_bipartite(non_bipartite_vector_graph,
boost::get(boost::vertex_index, non_bipartite_vector_graph), false);
check_bipartite(
non_bipartite_list_graph, non_bipartite_index_property_map, false);
/// Test some more interfaces
BOOST_TEST(is_bipartite(bipartite_vector_graph));
BOOST_TEST(!is_bipartite(non_bipartite_vector_graph));
return boost::report_errors();
}
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