Bocs, veletlen volt.
2 #ifndef HUGO_MINLENGTHPATHS_H
3 #define HUGO_MINLENGTHPATHS_H
7 ///\brief An algorithm for finding k paths of minimal total length.
11 #include <graph_wrapper.h>
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 ///\author Attila Bernath
30 template <typename Graph, typename LengthMap>
31 class MinLengthPaths {
33 typedef typename LengthMap::ValueType Length;
35 typedef typename Graph::Node Node;
36 typedef typename Graph::NodeIt NodeIt;
37 typedef typename Graph::Edge Edge;
38 typedef typename Graph::OutEdgeIt OutEdgeIt;
39 typedef typename Graph::template EdgeMap<int> EdgeIntMap;
41 typedef ConstMap<Edge,int> ConstMap;
43 typedef ResGraphWrapper<const Graph,int,ConstMap,EdgeIntMap> ResGraphType;
46 typedef typename ResGraphType::template NodeMap<Length> NodeMap;
47 const ResGraphType& G;
48 const EdgeIntMap& rev;
52 typedef typename LengthMap::KeyType KeyType;
53 typedef typename LengthMap::ValueType ValueType;
55 ValueType operator[](typename ResGraphType::Edge e) const {
56 //if ( (1-2*rev[e])*ol[e]-(pot[G.head(e)]-pot[G.tail(e)] ) <0 ){
57 // std::cout<<"Negative length!!"<<std::endl;
59 return (1-2*rev[e])*ol[e]-(pot[G.head(e)]-pot[G.tail(e)]);
62 ModLengthMap(const ResGraphType& _G, const EdgeIntMap& _rev,
63 const LengthMap &o, const NodeMap &p) :
64 G(_G), rev(_rev), ol(o), pot(p){};
71 const LengthMap& length;
75 //The value is 1 iff the edge is reversed.
76 //If the algorithm has finished, the edges of the seeked paths are
77 //exactly those that are reversed
80 //Container to store found paths
81 std::vector< std::vector<Edge> > paths;
82 //typedef DirPath<Graph> DPath;
91 MinLengthPaths(Graph& _G, LengthMap& _length) : G(_G),
92 length(_length), reversed(_G)/*, dijkstra_dist(_G)*/{ }
95 ///Runs the algorithm.
97 ///Runs the algorithm.
98 ///Returns k if there are at least k edge-disjoint paths from s to t.
99 ///Otherwise it returns the number of found edge-disjoint paths from s to t.
100 int run(Node s, Node t, int k) {
101 ConstMap const1map(1);
104 //We need a residual graph, in which some of the edges are reversed
105 ResGraphType res_graph(G, const1map, reversed);
107 //Initialize the copy of the Dijkstra potential to zero
108 typename ResGraphType::template NodeMap<Length> dijkstra_dist(res_graph);
109 ModLengthMap mod_length(res_graph, reversed, length, dijkstra_dist);
111 Dijkstra<ResGraphType, ModLengthMap> dijkstra(res_graph, mod_length);
116 if (!dijkstra.reached(t)){
117 //There are no k paths from s to t
122 //We have to copy the potential
123 typename ResGraphType::NodeIt n;
124 for ( res_graph.first(n) ; res_graph.valid(n) ; res_graph.next(n) ) {
125 dijkstra_dist[n] += dijkstra.distMap()[n];
130 //Reversing the sortest path
134 e = dijkstra.pred(n);
135 n = dijkstra.predNode(n);
136 reversed[e] = 1-reversed[e];
142 //Let's find the paths
143 //We put the paths into stl vectors (as an inner representation).
144 //In the meantime we lose the information stored in 'reversed'.
145 //We suppose the lengths to be positive now.
147 //Meanwhile we put the total length of the found paths
148 //in the member variable total_length
152 for (int j=0; j<i; ++j){
161 while (!reversed[e]){
165 paths[j].push_back(e);
166 total_length += length[e];
167 reversed[e] = 1-reversed[e];
175 ///This function gives back the total length of the found paths.
176 ///Assumes that \c run() has been run and nothing changed since then.
177 Length totalLength(){
181 ///This function gives back the \c j-th path in argument p.
182 ///Assumes that \c run() has been run and nothing changed since then.
183 /// \warning It is assumed that \c p is constructed to be a path of graph \c G. If \c j is greater than the result of previous \c run, then the result here will be an empty path.
184 template<typename DirPath>
185 void getPath(DirPath& p, int j){
187 typename DirPath::Builder B(p);
188 for(typename std::vector<Edge>::iterator i=paths[j].begin();
189 i!=paths[j].end(); ++i ){
196 }; //class MinLengthPaths
202 #endif //HUGO_MINLENGTHPATHS_H