[222] | 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 | //Alpar: Changed the order of the parameters |
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| 35 | template <typename Graph, |
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| 36 | typename LengthMap=typename Graph::EdgeMap<int>, |
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| 37 | typename Heap=FibHeap<typename Graph::Node, |
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| 38 | typename LengthMap::ValueType, |
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| 39 | typename Graph::NodeMap<int> > > |
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| 40 | class Dijkstra{ |
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| 41 | public: |
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| 42 | typedef typename LengthMap::ValueType ValueType; |
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| 43 | |
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| 44 | private: |
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| 45 | typedef typename Graph::Node Node; |
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| 46 | typedef typename Graph::NodeIt NodeIt; |
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| 47 | typedef typename Graph::Edge Edge; |
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| 48 | typedef typename Graph::OutEdgeIt OutEdgeIt; |
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| 49 | |
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| 50 | const Graph& G; |
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| 51 | const LengthMap& length; |
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| 52 | typedef typename Graph::NodeMap<Edge> PredMap; |
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| 53 | PredMap predecessor; |
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| 54 | //In place of reach: |
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| 55 | typedef typename Graph::NodeMap<Node> PredNodeMap; |
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| 56 | PredNodeMap pred_node; |
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| 57 | typedef typename Graph::NodeMap<ValueType> DistMap; |
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| 58 | DistMap distance; |
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| 59 | //I don't like this: |
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| 60 | // //FIXME: |
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| 61 | // typename Graph::NodeMap<bool> reach; |
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| 62 | // //typename Graph::NodeMap<int> reach; |
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| 63 | |
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| 64 | public : |
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| 65 | |
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| 66 | /* |
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| 67 | The distance of the nodes is 0. |
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| 68 | */ |
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| 69 | Dijkstra(Graph& _G, LengthMap& _length) : |
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| 70 | G(_G), length(_length), predecessor(_G), pred_node(_G), distance(_G) { } |
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| 71 | |
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| 72 | |
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| 73 | void run(Node s); |
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| 74 | |
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| 75 | ValueType dist(Node v) const { return distance[v]; } |
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| 76 | Edge pred(Node v) const { return predecessor[v]; } |
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| 77 | Node predNode(Node v) const { return pred_node[v]; } |
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| 78 | |
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| 79 | const DistMap &distMap() const { return distance;} |
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| 80 | const PredMap &predMap() const { return predecessor;} |
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| 81 | const PredNodeMap &predNodeMap() const { return pred_node;} |
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| 82 | |
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| 83 | // bool reached(Node v) { return reach[v]; } |
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| 84 | ///\warning \c s is not reached! |
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| 85 | /// |
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| 86 | bool reached(Node v) { return G.valid(predecessor[v]); } |
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| 87 | |
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| 88 | }; |
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| 89 | |
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| 90 | |
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| 91 | // IMPLEMENTATIONS |
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| 92 | |
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| 93 | template <typename Graph, typename LengthMap, typename Heap > |
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| 94 | void Dijkstra<Graph,LengthMap,Heap>::run(Node s) { |
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| 95 | |
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| 96 | NodeIt u; |
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| 97 | for ( G.first(u) ; G.valid(u) ; G.next(u) ) { |
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| 98 | predecessor.set(u,INVALID); |
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| 99 | // If a node is unreacheable, then why should be the dist=0? |
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| 100 | // distance.set(u,0); |
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| 101 | // reach.set(u,false); |
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| 102 | } |
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| 103 | |
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| 104 | //We don't need it at all. |
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| 105 | // //FIXME: |
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| 106 | // typename Graph::NodeMap<bool> scanned(G,false); |
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| 107 | // //typename Graph::NodeMap<int> scanned(G,false); |
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| 108 | typename Graph::NodeMap<int> heap_map(G,-1); |
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| 109 | |
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| 110 | Heap heap(heap_map); |
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| 111 | |
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| 112 | heap.push(s,0); |
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| 113 | // reach.set(s, true); |
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| 114 | |
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| 115 | while ( !heap.empty() ) { |
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| 116 | |
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| 117 | Node v=heap.top(); |
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| 118 | ValueType oldvalue=heap[v]; |
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| 119 | heap.pop(); |
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| 120 | distance.set(v, oldvalue); |
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| 121 | |
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| 122 | for(OutEdgeIt e(G,v); G.valid(e); G.next(e)) { |
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| 123 | Node w=G.head(e); |
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| 124 | |
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| 125 | switch(heap.state(w)) { |
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| 126 | case Heap::PRE_HEAP: |
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| 127 | // reach.set(w,true); |
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| 128 | heap.push(w,oldvalue+length[e]); |
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| 129 | predecessor.set(w,e); |
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| 130 | pred_node.set(w,v); |
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| 131 | break; |
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| 132 | case Heap::IN_HEAP: |
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| 133 | if ( oldvalue+length[e] < heap[w] ) { |
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| 134 | heap.decrease(w, oldvalue+length[e]); |
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| 135 | predecessor.set(w,e); |
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| 136 | pred_node.set(w,v); |
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| 137 | } |
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| 138 | break; |
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| 139 | case Heap::POST_HEAP: |
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| 140 | break; |
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| 141 | } |
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| 142 | } |
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| 143 | } |
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| 144 | } |
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| 145 | |
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| 146 | } //END OF NAMESPACE HUGO |
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| 147 | |
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| 148 | #endif |
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| 149 | |
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| 150 | |
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