241 lines
8.5 KiB
C++
241 lines
8.5 KiB
C++
//
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//=======================================================================
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// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
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// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
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//
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// Distributed under the Boost Software License, Version 1.0. (See
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// accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//=======================================================================
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//
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/*
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This file implements the function
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template <class EdgeListGraph, class Size, class P, class T, class R>
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bool bellman_ford_shortest_paths(EdgeListGraph& g, Size N,
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const bgl_named_params<P, T, R>& params)
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*/
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#ifndef BOOST_GRAPH_BELLMAN_FORD_SHORTEST_PATHS_HPP
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#define BOOST_GRAPH_BELLMAN_FORD_SHORTEST_PATHS_HPP
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#include <boost/config.hpp>
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#include <boost/graph/graph_traits.hpp>
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#include <boost/graph/graph_concepts.hpp>
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#include <boost/graph/properties.hpp>
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#include <boost/graph/relax.hpp>
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#include <boost/graph/visitors.hpp>
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#include <boost/graph/named_function_params.hpp>
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#include <boost/concept/assert.hpp>
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namespace boost {
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template <class Visitor, class Graph>
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struct BellmanFordVisitorConcept {
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void constraints() {
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BOOST_CONCEPT_ASSERT(( CopyConstructibleConcept<Visitor> ));
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vis.examine_edge(e, g);
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vis.edge_relaxed(e, g);
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vis.edge_not_relaxed(e, g);
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vis.edge_minimized(e, g);
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vis.edge_not_minimized(e, g);
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}
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Visitor vis;
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Graph g;
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typename graph_traits<Graph>::edge_descriptor e;
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};
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template <class Visitors = null_visitor>
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class bellman_visitor {
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public:
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bellman_visitor() { }
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bellman_visitor(Visitors vis) : m_vis(vis) { }
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template <class Edge, class Graph>
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void examine_edge(Edge u, Graph& g) {
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invoke_visitors(m_vis, u, g, on_examine_edge());
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}
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template <class Edge, class Graph>
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void edge_relaxed(Edge u, Graph& g) {
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invoke_visitors(m_vis, u, g, on_edge_relaxed());
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}
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template <class Edge, class Graph>
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void edge_not_relaxed(Edge u, Graph& g) {
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invoke_visitors(m_vis, u, g, on_edge_not_relaxed());
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}
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template <class Edge, class Graph>
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void edge_minimized(Edge u, Graph& g) {
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invoke_visitors(m_vis, u, g, on_edge_minimized());
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}
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template <class Edge, class Graph>
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void edge_not_minimized(Edge u, Graph& g) {
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invoke_visitors(m_vis, u, g, on_edge_not_minimized());
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}
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protected:
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Visitors m_vis;
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};
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template <class Visitors>
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bellman_visitor<Visitors>
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make_bellman_visitor(Visitors vis) {
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return bellman_visitor<Visitors>(vis);
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}
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typedef bellman_visitor<> default_bellman_visitor;
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template <class EdgeListGraph, class Size, class WeightMap,
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class PredecessorMap, class DistanceMap,
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class BinaryFunction, class BinaryPredicate,
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class BellmanFordVisitor>
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bool bellman_ford_shortest_paths(EdgeListGraph& g, Size N,
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WeightMap weight,
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PredecessorMap pred,
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DistanceMap distance,
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BinaryFunction combine,
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BinaryPredicate compare,
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BellmanFordVisitor v)
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{
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BOOST_CONCEPT_ASSERT(( EdgeListGraphConcept<EdgeListGraph> ));
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typedef graph_traits<EdgeListGraph> GTraits;
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typedef typename GTraits::edge_descriptor Edge;
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typedef typename GTraits::vertex_descriptor Vertex;
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BOOST_CONCEPT_ASSERT(( ReadWritePropertyMapConcept<DistanceMap, Vertex> ));
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BOOST_CONCEPT_ASSERT(( ReadablePropertyMapConcept<WeightMap, Edge> ));
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typename GTraits::edge_iterator i, end;
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for (Size k = 0; k < N; ++k) {
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bool at_least_one_edge_relaxed = false;
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for (boost::tie(i, end) = edges(g); i != end; ++i) {
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v.examine_edge(*i, g);
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if (relax(*i, g, weight, pred, distance, combine, compare)) {
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at_least_one_edge_relaxed = true;
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v.edge_relaxed(*i, g);
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} else
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v.edge_not_relaxed(*i, g);
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}
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if (!at_least_one_edge_relaxed)
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break;
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}
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for (boost::tie(i, end) = edges(g); i != end; ++i)
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if (compare(combine(get(distance, source(*i, g)), get(weight, *i)),
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get(distance, target(*i,g))))
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{
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v.edge_not_minimized(*i, g);
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return false;
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} else
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v.edge_minimized(*i, g);
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return true;
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}
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namespace detail {
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template<typename VertexAndEdgeListGraph, typename Size,
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typename WeightMap, typename PredecessorMap, typename DistanceMap,
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typename P, typename T, typename R>
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bool
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bellman_dispatch2
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(VertexAndEdgeListGraph& g,
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typename graph_traits<VertexAndEdgeListGraph>::vertex_descriptor s,
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Size N, WeightMap weight, PredecessorMap pred, DistanceMap distance,
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const bgl_named_params<P, T, R>& params)
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{
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typedef typename property_traits<DistanceMap>::value_type D;
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bellman_visitor<> null_vis;
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typedef typename property_traits<WeightMap>::value_type weight_type;
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typename graph_traits<VertexAndEdgeListGraph>::vertex_iterator v, v_end;
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for (boost::tie(v, v_end) = vertices(g); v != v_end; ++v) {
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put(distance, *v, (std::numeric_limits<weight_type>::max)());
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put(pred, *v, *v);
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}
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put(distance, s, weight_type(0));
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return bellman_ford_shortest_paths
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(g, N, weight, pred, distance,
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choose_param(get_param(params, distance_combine_t()),
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closed_plus<D>()),
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choose_param(get_param(params, distance_compare_t()),
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std::less<D>()),
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choose_param(get_param(params, graph_visitor),
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null_vis)
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);
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}
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template<typename VertexAndEdgeListGraph, typename Size,
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typename WeightMap, typename PredecessorMap, typename DistanceMap,
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typename P, typename T, typename R>
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bool
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bellman_dispatch2
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(VertexAndEdgeListGraph& g,
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param_not_found,
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Size N, WeightMap weight, PredecessorMap pred, DistanceMap distance,
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const bgl_named_params<P, T, R>& params)
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{
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typedef typename property_traits<DistanceMap>::value_type D;
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bellman_visitor<> null_vis;
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return bellman_ford_shortest_paths
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(g, N, weight, pred, distance,
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choose_param(get_param(params, distance_combine_t()),
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closed_plus<D>()),
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choose_param(get_param(params, distance_compare_t()),
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std::less<D>()),
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choose_param(get_param(params, graph_visitor),
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null_vis)
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);
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}
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template <class EdgeListGraph, class Size, class WeightMap,
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class DistanceMap, class P, class T, class R>
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bool bellman_dispatch(EdgeListGraph& g, Size N,
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WeightMap weight, DistanceMap distance,
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const bgl_named_params<P, T, R>& params)
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{
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dummy_property_map dummy_pred;
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return
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detail::bellman_dispatch2
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(g,
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get_param(params, root_vertex_t()),
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N, weight,
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choose_param(get_param(params, vertex_predecessor), dummy_pred),
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distance,
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params);
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}
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} // namespace detail
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template <class EdgeListGraph, class Size, class P, class T, class R>
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bool bellman_ford_shortest_paths
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(EdgeListGraph& g, Size N,
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const bgl_named_params<P, T, R>& params)
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{
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return detail::bellman_dispatch
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(g, N,
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choose_const_pmap(get_param(params, edge_weight), g, edge_weight),
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choose_pmap(get_param(params, vertex_distance), g, vertex_distance),
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params);
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}
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template <class EdgeListGraph, class Size>
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bool bellman_ford_shortest_paths(EdgeListGraph& g, Size N)
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{
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bgl_named_params<int,int> params(0);
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return bellman_ford_shortest_paths(g, N, params);
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}
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template <class VertexAndEdgeListGraph, class P, class T, class R>
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bool bellman_ford_shortest_paths
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(VertexAndEdgeListGraph& g,
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const bgl_named_params<P, T, R>& params)
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{
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BOOST_CONCEPT_ASSERT(( VertexListGraphConcept<VertexAndEdgeListGraph> ));
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return detail::bellman_dispatch
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(g, num_vertices(g),
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choose_const_pmap(get_param(params, edge_weight), g, edge_weight),
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choose_pmap(get_param(params, vertex_distance), g, vertex_distance),
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params);
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}
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} // namespace boost
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#endif // BOOST_GRAPH_BELLMAN_FORD_SHORTEST_PATHS_HPP
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