boost/libs/graph/example/incremental-components-eg.cpp
2021-10-05 21:37:46 +02:00

87 lines
2.8 KiB
C++

//=======================================================================
// Copyright 2001 Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee,
// Copyright 2009 Trustees of Indiana University.
// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek, Michael Hansen
//
// 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 <iostream>
#include <vector>
#include <boost/foreach.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/incremental_components.hpp>
#include <boost/pending/disjoint_sets.hpp>
using namespace boost;
int main(int argc, char* argv[])
{
typedef adjacency_list< vecS, vecS, undirectedS > Graph;
typedef graph_traits< Graph >::vertex_descriptor Vertex;
// typedef graph_traits<Graph>::edge_descriptor Edge;
typedef graph_traits< Graph >::vertices_size_type VertexIndex;
// Create a graph
const int VERTEX_COUNT = 6;
Graph graph(VERTEX_COUNT);
add_edge(0, 1, graph);
add_edge(1, 4, graph);
// reate the disjoint-sets object, which requires rank and parent
// vertex properties.
std::vector< Vertex > rank(num_vertices(graph));
std::vector< Vertex > parent(num_vertices(graph));
typedef VertexIndex* Rank;
typedef Vertex* Parent;
disjoint_sets< Rank, Parent > ds(&rank[0], &parent[0]);
// Determine the connected components, storing the results in the
// disjoint-sets object.
initialize_incremental_components(graph, ds);
incremental_components(graph, ds);
// Add a couple more edges and update the disjoint-sets
add_edge(4, 0, graph);
add_edge(2, 5, graph);
ds.union_set(4, 0);
ds.union_set(2, 5);
BOOST_FOREACH (Vertex current_vertex, vertices(graph))
{
std::cout << "representative[" << current_vertex
<< "] = " << ds.find_set(current_vertex) << std::endl;
}
std::cout << std::endl;
// Generate component index. NOTE: We would need to pass in a vertex
// index map into the component_index constructor if our graph type
// used listS instead of vecS (identity_property_map is used by
// default).
typedef component_index< VertexIndex > Components;
Components components(parent.begin(), parent.end());
// Iterate through the component indices
BOOST_FOREACH (VertexIndex component_index, components)
{
std::cout << "component " << component_index << " contains: ";
// Iterate through the child vertex indices for [component_index]
BOOST_FOREACH (VertexIndex child_index, components[component_index])
{
std::cout << child_index << " ";
}
std::cout << std::endl;
}
return (0);
}