Remove one remaining range checking.
2 #ifndef HUGO_MINLENGTHPATHS_H
3 #define HUGO_MINLENGTHPATHS_H
7 ///\brief An algorithm for finding k paths of minimal total length.
10 //#include <hugo/dijkstra.h>
11 //#include <hugo/graph_wrapper.h>
12 #include <hugo/maps.h>
14 #include <hugo/mincostflows.h>
18 /// \addtogroup flowalgs
21 ///\brief Implementation of an algorithm for finding k paths between 2 nodes
22 /// of minimal total length
24 /// The class \ref hugo::MinLengthPaths "MinLengthPaths" implements
25 /// an algorithm for finding k edge-disjoint paths
26 /// from a given source node to a given target node in an
27 /// edge-weighted directed graph having minimal total weigth (length).
29 ///\warning It is assumed that the lengths are positive, since the
30 /// general flow-decomposition is not implemented yet.
32 ///\author Attila Bernath
33 template <typename Graph, typename LengthMap>
37 typedef typename LengthMap::ValueType Length;
39 typedef typename Graph::Node Node;
40 typedef typename Graph::NodeIt NodeIt;
41 typedef typename Graph::Edge Edge;
42 typedef typename Graph::OutEdgeIt OutEdgeIt;
43 typedef typename Graph::template EdgeMap<int> EdgeIntMap;
45 typedef ConstMap<Edge,int> ConstMap;
51 //This is the capacity map for the mincostflow problem
53 //This MinCostFlows instance will actually solve the problem
54 MinCostFlows<Graph, LengthMap, ConstMap> mincost_flow;
56 //Container to store found paths
57 std::vector< std::vector<Edge> > paths;
62 MinLengthPaths(Graph& _G, LengthMap& _length) : G(_G),
63 const1map(1), mincost_flow(_G, _length, const1map){}
65 ///Runs the algorithm.
67 ///Runs the algorithm.
68 ///Returns k if there are at least k edge-disjoint paths from s to t.
69 ///Otherwise it returns the number of found edge-disjoint paths from s to t.
70 int run(Node s, Node t, int k) {
72 int i = mincost_flow.run(s,t,k);
76 //Let's find the paths
77 //We put the paths into stl vectors (as an inner representation).
78 //In the meantime we lose the information stored in 'reversed'.
79 //We suppose the lengths to be positive now.
81 //We don't want to change the flow of mincost_flow, so we make a copy
82 //The name here suggests that the flow has only 0/1 values.
83 EdgeIntMap reversed(G);
85 for(typename Graph::EdgeIt e(G); e!=INVALID; ++e)
86 reversed[e] = mincost_flow.getFlow()[e];
91 for (int j=0; j<i; ++j){
100 while (!reversed[e]){
104 paths[j].push_back(e);
105 //total_length += length[e];
106 reversed[e] = 1-reversed[e];
114 ///This function gives back the total length of the found paths.
115 ///Assumes that \c run() has been run and nothing changed since then.
116 Length totalLength(){
117 return mincost_flow.totalLength();
120 ///Returns a const reference to the EdgeMap \c flow. \pre \ref run() must
121 ///be called before using this function.
122 const EdgeIntMap &getFlow() const { return mincost_flow.flow;}
124 ///Returns a const reference to the NodeMap \c potential (the dual solution).
125 /// \pre \ref run() must be called before using this function.
126 const EdgeIntMap &getPotential() const { return mincost_flow.potential;}
128 ///This function checks, whether the given solution is optimal
129 ///Running after a \c run() should return with true
130 ///In this "state of the art" this only checks optimality, doesn't bother with feasibility
132 ///\todo Is this OK here?
133 bool checkComplementarySlackness(){
134 return mincost_flow.checkComplementarySlackness();
137 ///This function gives back the \c j-th path in argument p.
138 ///Assumes that \c run() has been run and nothing changed since then.
139 /// \warning It is assumed that \c p is constructed to be a path of graph \c G. If \c j is not less than the result of previous \c run, then the result here will be an empty path (\c j can be 0 as well).
140 template<typename DirPath>
141 void getPath(DirPath& p, size_t j){
144 if (j>paths.size()-1){
147 typename DirPath::Builder B(p);
148 for(typename std::vector<Edge>::iterator i=paths[j].begin();
149 i!=paths[j].end(); ++i ){
156 }; //class MinLengthPaths
162 #endif //HUGO_MINLENGTHPATHS_H