fn() dijkstraComputes shortest paths from a single source in a graph.
Computes shortest paths from a single source in a graph.
Defined in | <seqan/graph_algorithms.h> |
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Signature |
void dijkstra(g, source, weight, predecessor, distance);
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Parameters
predecessor
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A property map. A property map that represents predecessor relationships among vertices. It determines a shortest-paths tree. |
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distance
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A property map.Indicates for each vertex the distance from the source. |
g
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A graph. Types: Directed Graph |
source
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A source vertex. Types: VertexDescriptor |
weight
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A weight map. A property map with edge weights. Edge weights have to be nonnegative. |
Detailed Description
Remarks
Edge weights have to be nonnegative.
Example
#include <iostream> #include <seqan/graph_algorithms.h> using namespace seqan; int main() { typedef Graph<Directed<> > TGraph; typedef VertexDescriptor<TGraph>::Type TVertexDescriptor; typedef EdgeDescriptor<TGraph>::Type TEdgeDescriptor; typedef Size<TGraph>::Type TSize; // Create graph with 10 directed edges (0,1), (0,3), ... TSize numEdges = 10; TVertexDescriptor edges[] = {0,1, 0,3, 1,2, 1,3, 2,4, 3,1, 3,2, 3,4, 4,0, 4,2}; TGraph g; addEdges(g, edges, numEdges); // Fill external edge weight map. unsigned weights[] = {10, 5, 1, 2, 4, 3, 9, 2, 7, 6}; String<unsigned> weightMap; assignEdgeMap(g, weightMap, weights); // Run Dijkstra's algorithm from vertex 0. String<unsigned> predMap; String<unsigned> distMap; dijkstra(g, 0, weightMap, predMap, distMap); // Print results to stdout. std::cout << "Single-Source Shortest Paths: \n"; typedef Iterator<TGraph, VertexIterator>::Type TVertexIterator; TVertexIterator it(g); while (!atEnd(it)) { std::cout << "Path from 0 to " << getValue(it) << ": "; _printPath(g,predMap,(TVertexDescriptor) 0, getValue(it)); std::cout << " (Distance: " << getProperty(distMap, getValue(it)) << ")\n"; goNext(it); } // We can achieve the same thing using an internal map that is edge cargos. typedef unsigned int TEdgeCargo; typedef Directed<TEdgeCargo> TEdges; typedef Graph<TEdges> TCargoGraph; // Construct graph with the same edges as above. TCargoGraph cargoG; addEdges(cargoG, edges, numEdges); // Fill internal edge weight map. InternalMap<TEdgeCargo> intMap; assignEdgeMap(cargoG, intMap, weights); // Run Dijkstra's algorithm from vertex 0. clear(predMap); clear(distMap); dijkstra(cargoG, 0, intMap, predMap, distMap); // Print result to stdout. std::cout << "\nSingle-Source Shortest Paths: \n"; typedef Iterator<TCargoGraph, VertexIterator>::Type TCargoVertexIterator; TCargoVertexIterator itC(cargoG); while (!atEnd(itC)) { std::cout << "Path from 0 to " << getValue(itC) << ": "; _printPath(g, predMap, (TVertexDescriptor)0, getValue(itC)); std::cout << " (Distance: " << getProperty(distMap, getValue(itC)) << ")\n"; goNext(itC); } return 0; }
Single-Source Shortest Paths: Path from 0 to 0: 0 (Distance: 0) Path from 0 to 1: 0,3,1 (Distance: 8) Path from 0 to 2: 0,3,1,2 (Distance: 9) Path from 0 to 3: 0,3 (Distance: 5) Path from 0 to 4: 0,3,4 (Distance: 7) Single-Source Shortest Paths: Path from 0 to 0: 0 (Distance: 0) Path from 0 to 1: 0,1 (Distance: 0) Path from 0 to 2: 0,1,2 (Distance: 0) Path from 0 to 3: 0,3 (Distance: 0) Path from 0 to 4: 0,1,2,4 (Distance: 0)