Cooorected some eroorrs.
2 #ifndef HUGO_DIJKSTRA_H
3 #define HUGO_DIJKSTRA_H
7 ///\brief Dijkstra algorithm.
9 #include <hugo/bin_heap.h>
10 #include <hugo/invalid.h>
17 ///%Dijkstra algorithm class.
19 ///This class provides an efficient implementation of %Dijkstra algorithm.
20 ///The edge lengths are passed to the algorithm using a
21 ///\ref ReadMapSkeleton "readable map",
22 ///so it is easy to change it to any kind of length.
24 ///The type of the length is determined by the \c ValueType of the length map.
26 ///It is also possible to change the underlying priority heap.
28 ///\param GR The graph type the algorithm runs on.
29 ///\param LM This read-only
32 ///lengths of the edges. It is read once for each edge, so the map
33 ///may involve in relatively time consuming process to compute the edge
34 ///length if it is necessary. The default map type is
35 ///\ref GraphSkeleton::EdgeMap "Graph::EdgeMap<int>"
36 ///\param Heap The heap type used by the %Dijkstra
37 ///algorithm. The default
38 ///is using \ref BinHeap "binary heap".
40 ///\author Jacint Szabo
41 ///\todo We need a typedef-names should be standardized.
44 template <typename GR,
48 template <typename GR,
49 typename LM=typename GR::template EdgeMap<int>,
50 template <class,class,class,class> class Heap = BinHeap >
54 ///The type of the underlying graph.
56 typedef typename Graph::Node Node;
57 typedef typename Graph::NodeIt NodeIt;
58 typedef typename Graph::Edge Edge;
59 typedef typename Graph::OutEdgeIt OutEdgeIt;
61 ///The type of the length of the edges.
62 typedef typename LM::ValueType ValueType;
63 ///The the type of the map that stores the edge lengths.
65 ///\brief The the type of the map that stores the last
66 ///edges of the shortest paths.
67 typedef typename Graph::template NodeMap<Edge> PredMap;
68 ///\brief The the type of the map that stores the last but one
69 ///nodes of the shortest paths.
70 typedef typename Graph::template NodeMap<Node> PredNodeMap;
71 ///The the type of the map that stores the dists of the nodes.
72 typedef typename Graph::template NodeMap<ValueType> DistMap;
78 PredNodeMap pred_node;
83 Dijkstra(const Graph& _G, const LM& _length) :
84 G(_G), length(_length), predecessor(_G), pred_node(_G), distance(_G) { }
88 ///The distance of a node from the root.
90 ///Returns the distance of a node from the root.
91 ///\pre \ref run() must be called before using this function.
92 ///\warning If node \c v in unreachable from the root the return value
93 ///of this funcion is undefined.
94 ValueType dist(Node v) const { return distance[v]; }
96 ///Returns the 'previous edge' of the shortest path tree.
98 ///For a node \c v it returns the 'previous edge' of the shortest path tree,
99 ///i.e. it returns the last edge from a shortest path from the root to \c
100 ///v. It is INVALID if \c v is unreachable from the root or if \c v=s. The
101 ///shortest path tree used here is equal to the shortest path tree used in
102 ///\ref predNode(Node v). \pre \ref run() must be called before using
104 Edge pred(Node v) const { return predecessor[v]; }
106 ///Returns the 'previous node' of the shortest path tree.
108 ///For a node \c v it returns the 'previous node' of the shortest path tree,
109 ///i.e. it returns the last but one node from a shortest path from the
110 ///root to \c /v. It is INVALID if \c v is unreachable from the root or if
111 ///\c v=s. The shortest path tree used here is equal to the shortest path
112 ///tree used in \ref pred(Node v). \pre \ref run() must be called before
113 ///using this function.
114 Node predNode(Node v) const { return pred_node[v]; }
116 ///Returns a reference to the NodeMap of distances.
118 ///Returns a reference to the NodeMap of distances. \pre \ref run() must
119 ///be called before using this function.
120 const DistMap &distMap() const { return distance;}
122 ///Returns a reference to the shortest path tree map.
124 ///Returns a reference to the NodeMap of the edges of the
125 ///shortest path tree.
126 ///\pre \ref run() must be called before using this function.
127 const PredMap &predMap() const { return predecessor;}
129 ///Returns a reference to the map of nodes of shortest paths.
131 ///Returns a reference to the NodeMap of the last but one nodes of the
132 ///shortest path tree.
133 ///\pre \ref run() must be called before using this function.
134 const PredNodeMap &predNodeMap() const { return pred_node;}
136 ///Checks if a node is reachable from the root.
138 ///Returns \c true if \c v is reachable from the root.
139 ///\warning the root node is reported to be unreached!
140 ///\todo Is this what we want?
141 ///\pre \ref run() must be called before using this function.
143 bool reached(Node v) { return G.valid(predecessor[v]); }
148 // **********************************************************************
150 // **********************************************************************
152 ///Runs %Dijkstra algorithm from node the root.
154 ///This method runs the %Dijkstra algorithm from a root node \c s
157 ///shortest path to each node. The algorithm computes
158 ///- The shortest path tree.
159 ///- The distance of each node from the root.
160 template <typename GR, typename LM,
161 template<class,class,class,class> class Heap >
162 void Dijkstra<GR,LM,Heap>::run(Node s) {
165 for ( G.first(u) ; G.valid(u) ; G.next(u) ) {
166 predecessor.set(u,INVALID);
167 pred_node.set(u,INVALID);
170 typename GR::template NodeMap<int> heap_map(G,-1);
172 typedef Heap<Node, ValueType, typename GR::template NodeMap<int>,
173 std::less<ValueType> >
176 HeapType heap(heap_map);
180 while ( !heap.empty() ) {
183 ValueType oldvalue=heap[v];
185 distance.set(v, oldvalue);
187 { //FIXME this bracket is for e to be local
190 G.valid(e); G.next(e)) {
193 switch(heap.state(w)) {
194 case HeapType::PRE_HEAP:
195 heap.push(w,oldvalue+length[e]);
196 predecessor.set(w,e);
199 case HeapType::IN_HEAP:
200 if ( oldvalue+length[e] < heap[w] ) {
201 heap.decrease(w, oldvalue+length[e]);
202 predecessor.set(w,e);
206 case HeapType::POST_HEAP:
210 } //FIXME tis bracket
216 } //END OF NAMESPACE HUGO