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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:45:59 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:45:59 +0000
commit19fcec84d8d7d21e796c7624e521b60d28ee21ed (patch)
tree42d26aa27d1e3f7c0b8bd3fd14e7d7082f5008dc /src/boost/libs/graph/example/bellman-example.cpp
parentInitial commit. (diff)
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Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/boost/libs/graph/example/bellman-example.cpp')
-rw-r--r--src/boost/libs/graph/example/bellman-example.cpp134
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diff --git a/src/boost/libs/graph/example/bellman-example.cpp b/src/boost/libs/graph/example/bellman-example.cpp
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+++ b/src/boost/libs/graph/example/bellman-example.cpp
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+//=======================================================================
+// Copyright 2001 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)
+//=======================================================================
+#include <boost/config.hpp>
+#include <vector>
+#include <iostream>
+#include <fstream>
+#include <iomanip>
+#include <boost/graph/adjacency_list.hpp>
+#include <boost/graph/bellman_ford_shortest_paths.hpp>
+
+using namespace boost;
+
+template < typename Graph, typename ParentMap > struct edge_writer
+{
+ edge_writer(const Graph& g, const ParentMap& p) : m_g(g), m_parent(p) {}
+
+ template < typename Edge >
+ void operator()(std::ostream& out, const Edge& e) const
+ {
+ out << "[label=\"" << get(edge_weight, m_g, e) << "\"";
+ typename graph_traits< Graph >::vertex_descriptor u = source(e, m_g),
+ v = target(e, m_g);
+ if (m_parent[v] == u)
+ out << ", color=\"black\"";
+ else
+ out << ", color=\"grey\"";
+ out << "]";
+ }
+ const Graph& m_g;
+ ParentMap m_parent;
+};
+template < typename Graph, typename Parent >
+edge_writer< Graph, Parent > make_edge_writer(const Graph& g, const Parent& p)
+{
+ return edge_writer< Graph, Parent >(g, p);
+}
+
+struct EdgeProperties
+{
+ int weight;
+};
+
+int main()
+{
+ enum
+ {
+ u,
+ v,
+ x,
+ y,
+ z,
+ N
+ };
+ char name[] = { 'u', 'v', 'x', 'y', 'z' };
+ typedef std::pair< int, int > E;
+ const int n_edges = 10;
+ E edge_array[] = { E(u, y), E(u, x), E(u, v), E(v, u), E(x, y), E(x, v),
+ E(y, v), E(y, z), E(z, u), E(z, x) };
+ int weight[n_edges] = { -4, 8, 5, -2, 9, -3, 7, 2, 6, 7 };
+
+ typedef adjacency_list< vecS, vecS, directedS, no_property, EdgeProperties >
+ Graph;
+#if defined(BOOST_MSVC) && BOOST_MSVC <= 1300
+ // VC++ can't handle the iterator constructor
+ Graph g(N);
+ for (std::size_t j = 0; j < n_edges; ++j)
+ add_edge(edge_array[j].first, edge_array[j].second, g);
+#else
+ Graph g(edge_array, edge_array + n_edges, N);
+#endif
+ graph_traits< Graph >::edge_iterator ei, ei_end;
+ property_map< Graph, int EdgeProperties::* >::type weight_pmap
+ = get(&EdgeProperties::weight, g);
+ int i = 0;
+ for (boost::tie(ei, ei_end) = edges(g); ei != ei_end; ++ei, ++i)
+ weight_pmap[*ei] = weight[i];
+
+ std::vector< int > distance(N, (std::numeric_limits< short >::max)());
+ std::vector< std::size_t > parent(N);
+ for (i = 0; i < N; ++i)
+ parent[i] = i;
+ distance[z] = 0;
+
+#if defined(BOOST_MSVC) && BOOST_MSVC <= 1300
+ bool r = bellman_ford_shortest_paths(g, int(N), weight_pmap, &parent[0],
+ &distance[0], closed_plus< int >(), std::less< int >(),
+ default_bellman_visitor());
+#else
+ bool r = bellman_ford_shortest_paths(g, int(N),
+ weight_map(weight_pmap)
+ .distance_map(&distance[0])
+ .predecessor_map(&parent[0]));
+#endif
+
+ if (r)
+ for (i = 0; i < N; ++i)
+ std::cout << name[i] << ": " << std::setw(3) << distance[i] << " "
+ << name[parent[i]] << std::endl;
+ else
+ std::cout << "negative cycle" << std::endl;
+
+ std::ofstream dot_file("figs/bellman-eg.dot");
+ dot_file << "digraph D {\n"
+ << " rankdir=LR\n"
+ << " size=\"5,3\"\n"
+ << " ratio=\"fill\"\n"
+ << " edge[style=\"bold\"]\n"
+ << " node[shape=\"circle\"]\n";
+
+ {
+ for (boost::tie(ei, ei_end) = edges(g); ei != ei_end; ++ei)
+ {
+ graph_traits< Graph >::edge_descriptor e = *ei;
+ graph_traits< Graph >::vertex_descriptor u = source(e, g),
+ v = target(e, g);
+ // VC++ doesn't like the 3-argument get function, so here
+ // we workaround by using 2-nested get()'s.
+ dot_file << name[u] << " -> " << name[v] << "[label=\""
+ << get(get(&EdgeProperties::weight, g), e) << "\"";
+ if (parent[v] == u)
+ dot_file << ", color=\"black\"";
+ else
+ dot_file << ", color=\"grey\"";
+ dot_file << "]";
+ }
+ }
+ dot_file << "}";
+ return EXIT_SUCCESS;
+}