Moved the gui to glemon/trunk.
3 * This file is a part of LEMON, a generic C++ optimization library
5 * Copyright (C) 2003-2006
6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
7 * (Egervary Research Group on Combinatorial Optimization, EGRES).
9 * Permission to use, modify and distribute this software is granted
10 * provided that this copyright notice appears in all copies. For
11 * precise terms see the accompanying LICENSE file.
13 * This software is provided "AS IS" with no warranty of any kind,
14 * express or implied, and with no claim as to its suitability for any
19 #ifndef LEMON_SUURBALLE_H
20 #define LEMON_SUURBALLE_H
24 ///\brief An algorithm for finding k paths of minimal total length.
27 #include <lemon/maps.h>
29 #include <lemon/min_cost_flow.h>
33 /// \addtogroup flowalgs
36 ///\brief Implementation of an algorithm for finding k edge-disjoint paths between 2 nodes
37 /// of minimal total length
39 /// The class \ref lemon::Suurballe implements
40 /// an algorithm for finding k edge-disjoint paths
41 /// from a given source node to a given target node in an
42 /// edge-weighted directed graph having minimal total weight (length).
44 ///\warning Length values should be nonnegative!
46 ///\param Graph The directed graph type the algorithm runs on.
47 ///\param LengthMap The type of the length map (values should be nonnegative).
49 ///\note It it questionable whether it is correct to call this method after
50 ///%Suurballe for it is just a special case of Edmonds' and Karp's algorithm
51 ///for finding minimum cost flows. In fact, this implementation just
52 ///wraps the MinCostFlow algorithms. The paper of both %Suurballe and
53 ///Edmonds-Karp published in 1972, therefore it is possibly right to
54 ///state that they are
55 ///independent results. Most frequently this special case is referred as
56 ///%Suurballe method in the literature, especially in communication
58 ///\author Attila Bernath
59 template <typename Graph, typename LengthMap>
63 typedef typename LengthMap::Value Length;
65 typedef typename Graph::Node Node;
66 typedef typename Graph::NodeIt NodeIt;
67 typedef typename Graph::Edge Edge;
68 typedef typename Graph::OutEdgeIt OutEdgeIt;
69 typedef typename Graph::template EdgeMap<int> EdgeIntMap;
71 typedef ConstMap<Edge,int> ConstMap;
79 //This is the capacity map for the mincostflow problem
81 //This MinCostFlow instance will actually solve the problem
82 MinCostFlow<Graph, LengthMap, ConstMap> min_cost_flow;
84 //Container to store found paths
85 std::vector< std::vector<Edge> > paths;
90 /*! \brief The constructor of the class.
92 \param _G The directed graph the algorithm runs on.
93 \param _length The length (weight or cost) of the edges.
94 \param _s Source node.
95 \param _t Target node.
97 Suurballe(Graph& _G, LengthMap& _length, Node _s, Node _t) :
98 G(_G), s(_s), t(_t), const1map(1),
99 min_cost_flow(_G, _length, const1map, _s, _t) { }
101 ///Runs the algorithm.
103 ///Runs the algorithm.
104 ///Returns k if there are at least k edge-disjoint paths from s to t.
105 ///Otherwise it returns the number of edge-disjoint paths found
108 ///\param k How many paths are we looking for?
111 int i = min_cost_flow.run(k);
113 //Let's find the paths
114 //We put the paths into stl vectors (as an inner representation).
115 //In the meantime we lose the information stored in 'reversed'.
116 //We suppose the lengths to be positive now.
118 //We don't want to change the flow of min_cost_flow, so we make a copy
119 //The name here suggests that the flow has only 0/1 values.
120 EdgeIntMap reversed(G);
122 for(typename Graph::EdgeIt e(G); e!=INVALID; ++e)
123 reversed[e] = min_cost_flow.getFlow()[e];
127 for (int j=0; j<i; ++j){
134 while (!reversed[e]){
138 paths[j].push_back(e);
139 reversed[e] = 1-reversed[e];
147 ///Returns the total length of the paths.
149 ///This function gives back the total length of the found paths.
150 Length totalLength(){
151 return min_cost_flow.totalLength();
154 ///Returns the found flow.
156 ///This function returns a const reference to the EdgeMap \c flow.
157 const EdgeIntMap &getFlow() const { return min_cost_flow.flow;}
159 /// Returns the optimal dual solution
161 ///This function returns a const reference to the NodeMap
162 ///\c potential (the dual solution).
163 const EdgeIntMap &getPotential() const { return min_cost_flow.potential;}
165 ///Checks whether the complementary slackness holds.
167 ///This function checks, whether the given solution is optimal.
168 ///Currently this function only checks optimality,
169 ///doesn't bother with feasibility.
170 ///It is meant for testing purposes.
171 bool checkComplementarySlackness(){
172 return min_cost_flow.checkComplementarySlackness();
175 ///Read the found paths.
177 ///This function gives back the \c j-th path in argument p.
178 ///Assumes that \c run() has been run and nothing has changed since then.
179 /// \warning It is assumed that \c p is constructed to
180 ///be a path of graph \c G.
181 ///If \c j is not less than the result of previous \c run,
182 ///then the result here will be an empty path (\c j can be 0 as well).
184 ///\param Path The type of the path structure to put the result to (must meet lemon path concept).
185 ///\param p The path to put the result to.
186 ///\param j Which path you want to get from the found paths (in a real application you would get the found paths iteratively).
187 template<typename Path>
188 void getPath(Path& p, size_t j){
191 if (j>paths.size()-1){
194 typename Path::Builder B(p);
195 for(typename std::vector<Edge>::iterator i=paths[j].begin();
196 i!=paths[j].end(); ++i ){
209 #endif //LEMON_SUURBALLE_H