1 | // -*- C++ -*- |
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2 | /* |
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3 | *template <Graph, T, Heap=FibHeap, LengthMap=Graph::EdgeMap<T> > |
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4 | * |
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5 | *Constructor: |
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6 | * |
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7 | *Dijkstra(Graph G, LengthMap length) |
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8 | * |
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9 | * |
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10 | *Methods: |
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11 | * |
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12 | *void run(Node s) |
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13 | * |
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14 | *T dist(Node v) : After run(s) was run, it returns the distance from s to v. |
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15 | * Returns T() if v is not reachable from s. |
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16 | * |
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17 | *Edge pred(Node v) : After run(s) was run, it returns the last |
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18 | * edge of a shortest s-v path. It is INVALID for s and for |
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19 | * the nodes not reachable from s. |
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20 | * |
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21 | *bool reached(Node v) : After run(s) was run, it is true iff v is |
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22 | * reachable from s |
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23 | * |
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24 | */ |
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25 | |
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26 | #ifndef HUGO_DIJKSTRA_H |
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27 | #define HUGO_DIJKSTRA_H |
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28 | |
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29 | #include <fib_heap.h> |
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30 | #include <invalid.h> |
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31 | |
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32 | namespace hugo { |
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33 | |
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34 | template <typename Graph, typename T, |
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35 | typename Heap=FibHeap<typename Graph::Node, T, |
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36 | typename Graph::NodeMap<int> >, |
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37 | typename LengthMap=typename Graph::EdgeMap<T> > |
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38 | class Dijkstra{ |
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39 | typedef typename Graph::Node Node; |
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40 | typedef typename Graph::NodeIt NodeIt; |
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41 | typedef typename Graph::Edge Edge; |
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42 | typedef typename Graph::OutEdgeIt OutEdgeIt; |
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43 | |
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44 | const Graph& G; |
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45 | const LengthMap& length; |
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46 | typename Graph::NodeMap<Edge> predecessor; |
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47 | typename Graph::NodeMap<T> distance; |
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48 | //FIXME: |
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49 | typename Graph::NodeMap<bool> reach; |
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50 | //typename Graph::NodeMap<int> reach; |
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51 | |
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52 | public : |
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53 | |
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54 | /* |
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55 | The distance of the nodes is 0. |
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56 | */ |
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57 | Dijkstra(Graph& _G, LengthMap& _length) : G(_G), |
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58 | length(_length), predecessor(_G), distance(_G), reach(_G) { } |
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59 | |
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60 | |
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61 | void run(Node s) { |
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62 | |
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63 | NodeIt u; |
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64 | for ( G.first(u) ; G.valid(u) ; G.next(u) ) { |
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65 | predecessor.set(u,INVALID); |
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66 | distance.set(u,0); |
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67 | reach.set(u,false); |
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68 | } |
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69 | |
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70 | //FIXME: |
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71 | typename Graph::NodeMap<bool> scanned(G,false); |
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72 | //typename Graph::NodeMap<int> scanned(G,false); |
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73 | typename Graph::NodeMap<int> heap_map(G,-1); |
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74 | |
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75 | Heap heap(heap_map); |
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76 | |
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77 | heap.push(s,0); |
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78 | reach.set(s, true); |
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79 | |
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80 | while ( !heap.empty() ) { |
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81 | |
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82 | Node v=heap.top(); |
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83 | T oldvalue=heap[v]; |
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84 | heap.pop(); |
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85 | distance.set(v, oldvalue); |
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86 | scanned.set(v,true); |
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87 | |
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88 | OutEdgeIt e; |
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89 | for( G.first(e,v); G.valid(e); G.next(e)) { |
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90 | Node w=G.head(e); |
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91 | |
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92 | if ( !scanned[w] ) { |
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93 | if ( !reach[w] ) { |
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94 | reach.set(w,true); |
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95 | heap.push(w,oldvalue+length[e]); |
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96 | predecessor.set(w,e); |
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97 | } else if ( oldvalue+length[e] < heap[w] ) { |
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98 | predecessor.set(w,e); |
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99 | heap.decrease(w, oldvalue+length[e]); |
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100 | } |
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101 | } |
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102 | } |
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103 | } |
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104 | } |
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105 | |
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106 | T dist(Node v) { |
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107 | return distance[v]; |
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108 | } |
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109 | |
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110 | Edge pred(Node v) { |
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111 | return predecessor[v]; |
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112 | } |
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113 | |
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114 | bool reached(Node v) { |
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115 | return reach[v]; |
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116 | } |
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117 | |
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118 | }; |
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119 | |
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120 | } |
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121 | |
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122 | #endif |
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123 | |
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124 | |
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