ecency-mobile/ios/Pods/boost-for-react-native/boost/graph/random_spanning_tree.hpp

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// Copyright 2010 The Trustees of Indiana University.
// 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)
// Authors: Jeremiah Willcock
// Andrew Lumsdaine
#ifndef BOOST_GRAPH_RANDOM_SPANNING_TREE_HPP
#define BOOST_GRAPH_RANDOM_SPANNING_TREE_HPP
#include <vector>
#include <boost/assert.hpp>
#include <boost/graph/loop_erased_random_walk.hpp>
#include <boost/graph/random.hpp>
#include <boost/graph/iteration_macros.hpp>
#include <boost/property_map/property_map.hpp>
#include <boost/config.hpp>
#include <boost/graph/graph_traits.hpp>
#include <boost/graph/graph_concepts.hpp>
#include <boost/graph/properties.hpp>
#include <boost/graph/named_function_params.hpp>
namespace boost {
namespace detail {
// Use Wilson's algorithm (based on loop-free random walks) to generate a
// random spanning tree. The distribution of edges used is controlled by
// the next_edge() function, so this version allows either weighted or
// unweighted selection of trees.
// Algorithm is from http://en.wikipedia.org/wiki/Uniform_spanning_tree
template <typename Graph, typename PredMap, typename ColorMap, typename NextEdge>
void random_spanning_tree_internal(const Graph& g, typename graph_traits<Graph>::vertex_descriptor s, PredMap pred, ColorMap color, NextEdge next_edge) {
typedef typename graph_traits<Graph>::vertex_descriptor vertex_descriptor;
BOOST_ASSERT (num_vertices(g) >= 1); // g must also be undirected (or symmetric) and connected
typedef color_traits<typename property_traits<ColorMap>::value_type> color_gen;
BGL_FORALL_VERTICES_T(v, g, Graph) put(color, v, color_gen::white());
std::vector<vertex_descriptor> path;
put(color, s, color_gen::black());
put(pred, s, graph_traits<Graph>::null_vertex());
BGL_FORALL_VERTICES_T(v, g, Graph) {
if (get(color, v) != color_gen::white()) continue;
loop_erased_random_walk(g, v, next_edge, color, path);
for (typename std::vector<vertex_descriptor>::const_reverse_iterator i = path.rbegin();
boost::next(i) !=
(typename std::vector<vertex_descriptor>::const_reverse_iterator)path.rend();
++i) {
typename std::vector<vertex_descriptor>::const_reverse_iterator j = i;
++j;
BOOST_ASSERT (get(color, *j) == color_gen::gray());
put(color, *j, color_gen::black());
put(pred, *j, *i);
}
}
}
}
// Compute a uniformly-distributed spanning tree on a graph. Use Wilson's algorithm:
// @inproceedings{wilson96generating,
// author = {Wilson, David Bruce},
// title = {Generating random spanning trees more quickly than the cover time},
// booktitle = {STOC '96: Proceedings of the twenty-eighth annual ACM symposium on Theory of computing},
// year = {1996},
// isbn = {0-89791-785-5},
// pages = {296--303},
// location = {Philadelphia, Pennsylvania, United States},
// doi = {http://doi.acm.org/10.1145/237814.237880},
// publisher = {ACM},
// address = {New York, NY, USA},
// }
//
template <typename Graph, typename Gen, typename PredMap, typename ColorMap>
void random_spanning_tree(const Graph& g, Gen& gen, typename graph_traits<Graph>::vertex_descriptor root,
PredMap pred, static_property_map<double>, ColorMap color) {
unweighted_random_out_edge_gen<Graph, Gen> random_oe(gen);
detail::random_spanning_tree_internal(g, root, pred, color, random_oe);
}
// Compute a weight-distributed spanning tree on a graph.
template <typename Graph, typename Gen, typename PredMap, typename WeightMap, typename ColorMap>
void random_spanning_tree(const Graph& g, Gen& gen, typename graph_traits<Graph>::vertex_descriptor root,
PredMap pred, WeightMap weight, ColorMap color) {
weighted_random_out_edge_gen<Graph, WeightMap, Gen> random_oe(weight, gen);
detail::random_spanning_tree_internal(g, root, pred, color, random_oe);
}
template <typename Graph, typename Gen, typename P, typename T, typename R>
void random_spanning_tree(const Graph& g, Gen& gen, const bgl_named_params<P, T, R>& params) {
using namespace boost::graph::keywords;
typedef bgl_named_params<P, T, R> params_type;
BOOST_GRAPH_DECLARE_CONVERTED_PARAMETERS(params_type, params)
random_spanning_tree(g,
gen,
arg_pack[_root_vertex | *vertices(g).first],
arg_pack[_predecessor_map],
arg_pack[_weight_map | static_property_map<double>(1.)],
boost::detail::make_color_map_from_arg_pack(g, arg_pack));
}
}
#include <boost/graph/iteration_macros_undef.hpp>
#endif // BOOST_GRAPH_RANDOM_SPANNING_TREE_HPP