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182 lines
6.5 KiB
C++
182 lines
6.5 KiB
C++
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//=======================================================================
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// Copyright 2013 University of Warsaw.
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// Authors: Piotr Wygocki
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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 algorithm is described in "Network Flows: Theory, Algorithms, and Applications"
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// by Ahuja, Magnanti, Orlin.
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#ifndef BOOST_GRAPH_CYCLE_CANCELING_HPP
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#define BOOST_GRAPH_CYCLE_CANCELING_HPP
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#include <numeric>
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#include <boost/property_map/property_map.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/pending/indirect_cmp.hpp>
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#include <boost/pending/relaxed_heap.hpp>
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#include <boost/graph/bellman_ford_shortest_paths.hpp>
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#include <boost/graph/iteration_macros.hpp>
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#include <boost/graph/detail/augment.hpp>
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#include <boost/graph/find_flow_cost.hpp>
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namespace boost {
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namespace detail {
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template <typename PredEdgeMap, typename Vertex>
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class RecordEdgeMapAndCycleVertex
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: public bellman_visitor<edge_predecessor_recorder<PredEdgeMap, on_edge_relaxed> > {
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typedef edge_predecessor_recorder<PredEdgeMap, on_edge_relaxed> PredRec;
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public:
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RecordEdgeMapAndCycleVertex(PredEdgeMap pred, Vertex & v) :
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bellman_visitor<PredRec>(PredRec(pred)), m_v(v), m_pred(pred) {}
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template <typename Graph, typename Edge>
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void edge_not_minimized(Edge e, const Graph & g) const {
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typename graph_traits<Graph>::vertices_size_type n = num_vertices(g) + 1;
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//edge e is not minimized but does not have to be on the negative weight cycle
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//to find vertex on negative wieight cycle we move n+1 times backword in the PredEdgeMap graph.
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while(n > 0) {
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e = get(m_pred, source(e, g));
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--n;
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}
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m_v = source(e, g);
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}
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private:
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Vertex & m_v;
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PredEdgeMap m_pred;
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};
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} //detail
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template <class Graph, class Pred, class Distance, class Reversed, class ResidualCapacity, class Weight>
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void cycle_canceling(const Graph &g, Weight weight, Reversed rev, ResidualCapacity residual_capacity, Pred pred, Distance distance) {
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typedef filtered_graph<const Graph, is_residual_edge<ResidualCapacity> > ResGraph;
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ResGraph gres = detail::residual_graph(g, residual_capacity);
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typedef graph_traits<ResGraph> ResGTraits;
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typedef graph_traits<Graph> GTraits;
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typedef typename ResGTraits::edge_descriptor edge_descriptor;
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typedef typename ResGTraits::vertex_descriptor vertex_descriptor;
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typename GTraits::vertices_size_type N = num_vertices(g);
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BGL_FORALL_VERTICES_T(v, g, Graph) {
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put(pred, v, edge_descriptor());
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put(distance, v, 0);
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}
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vertex_descriptor cycleStart;
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while(!bellman_ford_shortest_paths(gres, N,
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weight_map(weight).
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distance_map(distance).
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visitor(detail::RecordEdgeMapAndCycleVertex<Pred, vertex_descriptor>(pred, cycleStart)))) {
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detail::augment(g, cycleStart, cycleStart, pred, residual_capacity, rev);
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BGL_FORALL_VERTICES_T(v, g, Graph) {
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put(pred, v, edge_descriptor());
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put(distance, v, 0);
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}
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}
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}
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//in this namespace argument dispatching takes place
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namespace detail {
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template <class Graph, class P, class T, class R, class ResidualCapacity, class Weight, class Reversed, class Pred, class Distance>
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void cycle_canceling_dispatch2(
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const Graph &g,
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Weight weight,
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Reversed rev,
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ResidualCapacity residual_capacity,
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Pred pred,
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Distance dist,
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const bgl_named_params<P, T, R>& params) {
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cycle_canceling(g, weight, rev, residual_capacity, pred, dist);
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}
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//setting default distance map
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template <class Graph, class P, class T, class R, class Pred, class ResidualCapacity, class Weight, class Reversed>
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void cycle_canceling_dispatch2(
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Graph &g,
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Weight weight,
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Reversed rev,
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ResidualCapacity residual_capacity,
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Pred pred,
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param_not_found,
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const bgl_named_params<P, T, R>& params) {
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typedef typename property_traits<Weight>::value_type D;
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std::vector<D> d_map(num_vertices(g));
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cycle_canceling(g, weight, rev, residual_capacity, pred,
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make_iterator_property_map(d_map.begin(), choose_const_pmap(get_param(params, vertex_index), g, vertex_index)));
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}
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template <class Graph, class P, class T, class R, class ResidualCapacity, class Weight, class Reversed, class Pred>
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void cycle_canceling_dispatch1(
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Graph &g,
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Weight weight,
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Reversed rev,
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ResidualCapacity residual_capacity,
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Pred pred,
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const bgl_named_params<P, T, R>& params) {
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cycle_canceling_dispatch2(g, weight, rev,residual_capacity, pred,
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get_param(params, vertex_distance), params);
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}
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//setting default predecessors map
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template <class Graph, class P, class T, class R, class ResidualCapacity, class Weight, class Reversed>
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void cycle_canceling_dispatch1(
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Graph &g,
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Weight weight,
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Reversed rev,
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ResidualCapacity residual_capacity,
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param_not_found,
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const bgl_named_params<P, T, R>& params) {
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typedef typename graph_traits<Graph>::edge_descriptor edge_descriptor;
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std::vector<edge_descriptor> p_map(num_vertices(g));
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cycle_canceling_dispatch2(g, weight, rev, residual_capacity,
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make_iterator_property_map(p_map.begin(), choose_const_pmap(get_param(params, vertex_index), g, vertex_index)),
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get_param(params, vertex_distance), params);
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}
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}//detail
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template <class Graph, class P, class T, class R>
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void cycle_canceling(Graph &g,
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const bgl_named_params<P, T, R>& params) {
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cycle_canceling_dispatch1(g,
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choose_const_pmap(get_param(params, edge_weight), g, edge_weight),
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choose_const_pmap(get_param(params, edge_reverse), g, edge_reverse),
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choose_pmap(get_param(params, edge_residual_capacity),
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g, edge_residual_capacity),
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get_param(params, vertex_predecessor),
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params);
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}
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template <class Graph>
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void cycle_canceling(Graph &g) {
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bgl_named_params<int, buffer_param_t> params(0);
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cycle_canceling(g, params);
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}
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}
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#endif /* BOOST_GRAPH_CYCLE_CANCELING_HPP */
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