Compile checks added.
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 Graph The graph type the algorithm runs on.
29 ///\param LengthMap 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 LengthMap typedef
43 template <typename Graph,
47 template <typename Graph,
48 typename LengthMap=typename Graph::template EdgeMap<int>,
49 template <class,class,class,class> class Heap = BinHeap >
53 typedef typename Graph::Node Node;
54 typedef typename Graph::NodeIt NodeIt;
55 typedef typename Graph::Edge Edge;
56 typedef typename Graph::OutEdgeIt OutEdgeIt;
58 typedef typename LengthMap::ValueType ValueType;
59 typedef typename Graph::template NodeMap<Edge> PredMap;
60 typedef typename Graph::template NodeMap<Node> PredNodeMap;
61 typedef typename Graph::template NodeMap<ValueType> DistMap;
65 const LengthMap& length;
67 PredNodeMap pred_node;
72 Dijkstra(const Graph& _G, const LengthMap& _length) :
73 G(_G), length(_length), predecessor(_G), pred_node(_G), distance(_G) { }
77 ///The distance of a node from the root.
79 ///Returns the distance of a node from the root.
80 ///\pre \ref run() must be called before using this function.
81 ///\warning If node \c v in unreachable from the root the return value
82 ///of this funcion is undefined.
83 ValueType dist(Node v) const { return distance[v]; }
85 ///Returns the previous edge of the shortest path tree.
87 ///For a node \c v it returns the previous edge of the shortest path tree,
88 ///i.e. it returns the last edge from a shortest path from the root to \c
89 ///v. It is INVALID if \c v is unreachable from the root or if \c v=s. The
90 ///shortest path tree used here is equal to the shortest path tree used in
91 ///\ref predNode(Node v). \pre \ref run() must be called before using
93 Edge pred(Node v) const { return predecessor[v]; }
95 ///Returns the previous node of the shortest path tree.
97 ///For a node \c v it returns the previous node of the shortest path tree,
98 ///i.e. it returns the last but one node from a shortest path from the
99 ///root to \c /v. It is INVALID if \c v is unreachable from the root or if
100 ///\c v=s. The shortest path tree used here is equal to the shortest path
101 ///tree used in \ref pred(Node v). \pre \ref run() must be called before
102 ///using this function.
103 Node predNode(Node v) const { return pred_node[v]; }
105 ///Returns a reference to the NodeMap of distances.
107 ///Returns a reference to the NodeMap of distances. \pre \ref run() must
108 ///be called before using this function.
109 const DistMap &distMap() const { return distance;}
111 ///Returns a reference to the shortest path tree map.
113 ///Returns a reference to the NodeMap of the edges of the
114 ///shortest path tree.
115 ///\pre \ref run() must be called before using this function.
116 const PredMap &predMap() const { return predecessor;}
118 ///Returns a reference to the map of nodes of shortest paths.
120 ///Returns a reference to the NodeMap of the last but one nodes of the
121 ///shortest path tree.
122 ///\pre \ref run() must be called before using this function.
123 const PredNodeMap &predNodeMap() const { return pred_node;}
125 ///Checks if a node is reachable from the root.
127 ///Returns \c true if \c v is reachable from the root.
128 ///\warning the root node is reported to be unreached!
129 ///\todo Is this what we want?
130 ///\pre \ref run() must be called before using this function.
132 bool reached(Node v) { return G.valid(predecessor[v]); }
137 // **********************************************************************
139 // **********************************************************************
141 ///Runs %Dijkstra algorithm from node the root.
143 ///This method runs the %Dijkstra algorithm from a root node \c s
146 ///shortest path to each node. The algorithm computes
147 ///- The shortest path tree.
148 ///- The distance of each node from the root.
149 template <typename Graph, typename LengthMap,
150 template<class,class,class,class> class Heap >
151 void Dijkstra<Graph,LengthMap,Heap>::run(Node s) {
154 for ( G.first(u) ; G.valid(u) ; G.next(u) ) {
155 predecessor.set(u,INVALID);
156 pred_node.set(u,INVALID);
159 typename Graph::template NodeMap<int> heap_map(G,-1);
161 typedef Heap<Node, ValueType, typename Graph::template NodeMap<int>,
162 std::less<ValueType> >
165 HeapType heap(heap_map);
169 while ( !heap.empty() ) {
172 ValueType oldvalue=heap[v];
174 distance.set(v, oldvalue);
176 { //FIXME this bracket is for e to be local
179 G.valid(e); G.next(e)) {
182 switch(heap.state(w)) {
183 case HeapType::PRE_HEAP:
184 heap.push(w,oldvalue+length[e]);
185 predecessor.set(w,e);
188 case HeapType::IN_HEAP:
189 if ( oldvalue+length[e] < heap[w] ) {
190 heap.decrease(w, oldvalue+length[e]);
191 predecessor.set(w,e);
195 case HeapType::POST_HEAP:
199 } //FIXME tis bracket
205 } //END OF NAMESPACE HUGO