1 | // -*- C++ -*- |
---|
2 | /* |
---|
3 | *template <Graph, T, Heap=FibHeap, LengthMap=Graph::EdgeMap<T> > |
---|
4 | * |
---|
5 | *Constructor: |
---|
6 | * |
---|
7 | *Dijkstra(Graph G, LengthMap length) |
---|
8 | * |
---|
9 | * |
---|
10 | *Methods: |
---|
11 | * |
---|
12 | *void run(Node s) |
---|
13 | * |
---|
14 | *T dist(Node v) : After run(s) was run, it returns the distance from s to v. |
---|
15 | * Returns T() if v is not reachable from s. |
---|
16 | * |
---|
17 | *Edge pred(Node v) : After run(s) was run, it returns the last |
---|
18 | * edge of a shortest s-v path. It is INVALID for s and for |
---|
19 | * the nodes not reachable from s. |
---|
20 | * |
---|
21 | *bool reached(Node v) : After run(s) was run, it is true iff v is |
---|
22 | * reachable from s |
---|
23 | * |
---|
24 | */ |
---|
25 | |
---|
26 | #ifndef HUGO_DIJKSTRA_H |
---|
27 | #define HUGO_DIJKSTRA_H |
---|
28 | |
---|
29 | #include <fib_heap.h> |
---|
30 | #include <invalid.h> |
---|
31 | |
---|
32 | namespace hugo { |
---|
33 | |
---|
34 | template <typename Graph, typename T, |
---|
35 | typename Heap=FibHeap<typename Graph::Node, T, |
---|
36 | typename Graph::NodeMap<int> >, |
---|
37 | typename LengthMap=typename Graph::EdgeMap<T> > |
---|
38 | class Dijkstra{ |
---|
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 | |
---|
44 | const Graph& G; |
---|
45 | const LengthMap& length; |
---|
46 | typename Graph::NodeMap<Edge> predecessor; |
---|
47 | typename Graph::NodeMap<T> distance; |
---|
48 | typename Graph::NodeMap<bool> reach; |
---|
49 | |
---|
50 | public : |
---|
51 | |
---|
52 | /* |
---|
53 | The distance of the nodes is 0. |
---|
54 | */ |
---|
55 | Dijkstra(Graph& _G, LengthMap& _length) : G(_G), |
---|
56 | length(_length), predecessor(_G), distance(_G), reach(_G) { } |
---|
57 | |
---|
58 | |
---|
59 | void run(Node s) { |
---|
60 | |
---|
61 | NodeIt u; |
---|
62 | for ( G.first(u) ; G.valid(u) ; G.next(u) ) { |
---|
63 | predecessor.set(u,INVALID); |
---|
64 | distance.set(u,0); |
---|
65 | reach.set(u,false); |
---|
66 | } |
---|
67 | |
---|
68 | typename Graph::NodeMap<bool> scanned(G,false); |
---|
69 | typename Graph::NodeMap<int> heap_map(G,-1); |
---|
70 | |
---|
71 | Heap heap(heap_map); |
---|
72 | |
---|
73 | heap.push(s,0); |
---|
74 | reach.set(s, true); |
---|
75 | |
---|
76 | while ( !heap.empty() ) { |
---|
77 | |
---|
78 | Node v=heap.top(); |
---|
79 | T oldvalue=heap.get(v); |
---|
80 | heap.pop(); |
---|
81 | distance.set(v, oldvalue); |
---|
82 | scanned.set(v,true); |
---|
83 | |
---|
84 | OutEdgeIt e; |
---|
85 | for( G.first(e,v); G.valid(e); G.next(e)) { |
---|
86 | Node w=G.head(e); |
---|
87 | |
---|
88 | if ( !scanned[w] ) { |
---|
89 | if ( !reach[w] ) { |
---|
90 | reach.set(w,true); |
---|
91 | heap.push(w,oldvalue+length[e]); |
---|
92 | predecessor.set(w,e); |
---|
93 | } else if ( oldvalue+length[e] < heap.get(w) ) { |
---|
94 | predecessor.set(w,e); |
---|
95 | heap.decrease(w, oldvalue+length[e]); |
---|
96 | } |
---|
97 | } |
---|
98 | } |
---|
99 | } |
---|
100 | } |
---|
101 | |
---|
102 | |
---|
103 | T dist(Node v) { |
---|
104 | return distance[v]; |
---|
105 | } |
---|
106 | |
---|
107 | |
---|
108 | Edge pred(Node v) { |
---|
109 | return predecessor[v]; |
---|
110 | } |
---|
111 | |
---|
112 | |
---|
113 | bool reached(Node v) { |
---|
114 | return reach[v]; |
---|
115 | } |
---|
116 | |
---|
117 | }; |
---|
118 | |
---|
119 | } |
---|
120 | |
---|
121 | #endif |
---|
122 | |
---|
123 | |
---|