[866] | 1 | // -*- c++ -*- |
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| 2 | |
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| 3 | // Use a DIMACS max flow file as stdin. |
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| 4 | // sub_graph_wrapper_demo < dimacs_max_flow_file |
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[871] | 5 | // This program computes a maximum number of edge-disjoint shortest paths |
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[869] | 6 | // between s and t. |
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[866] | 7 | |
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| 8 | #include <iostream> |
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| 9 | #include <fstream> |
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| 10 | |
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[921] | 11 | #include <lemon/smart_graph.h> |
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| 12 | #include <lemon/dijkstra.h> |
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| 13 | #include <lemon/maps.h> |
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| 14 | #include <lemon/graph_wrapper.h> |
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| 15 | #include <lemon/dimacs.h> |
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| 16 | #include <lemon/preflow.h> |
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[931] | 17 | #include <tight_edge_filter_map.h> |
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[866] | 18 | |
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[921] | 19 | using namespace lemon; |
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[866] | 20 | |
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| 21 | using std::cout; |
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| 22 | using std::endl; |
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| 23 | |
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| 24 | int main() |
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| 25 | { |
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| 26 | typedef SmartGraph Graph; |
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| 27 | |
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| 28 | typedef Graph::Edge Edge; |
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| 29 | typedef Graph::Node Node; |
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| 30 | typedef Graph::EdgeIt EdgeIt; |
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| 31 | typedef Graph::NodeIt NodeIt; |
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| 32 | typedef Graph::EdgeMap<int> LengthMap; |
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| 33 | |
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| 34 | Graph g; |
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| 35 | Node s, t; |
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| 36 | LengthMap length(g); |
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| 37 | |
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| 38 | readDimacs(std::cin, g, length, s, t); |
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| 39 | |
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[986] | 40 | cout << "edges with lengths (of form id, source--length->target): " << endl; |
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[866] | 41 | for(EdgeIt e(g); e!=INVALID; ++e) |
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[986] | 42 | cout << " " << g.id(e) << ", " << g.id(g.source(e)) << "--" |
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| 43 | << length[e] << "->" << g.id(g.target(e)) << endl; |
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[866] | 44 | |
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| 45 | cout << "s: " << g.id(s) << " t: " << g.id(t) << endl; |
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| 46 | |
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| 47 | typedef Dijkstra<Graph, LengthMap> Dijkstra; |
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| 48 | Dijkstra dijkstra(g, length); |
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| 49 | dijkstra.run(s); |
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| 50 | |
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[869] | 51 | // This map returns true exactly for those edges which are |
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| 52 | // tight w.r.t the length funcion and the potential |
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| 53 | // given by the dijkstra algorithm. |
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[866] | 54 | typedef TightEdgeFilterMap<Graph, const Dijkstra::DistMap, LengthMap> |
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| 55 | TightEdgeFilter; |
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| 56 | TightEdgeFilter tight_edge_filter(g, dijkstra.distMap(), length); |
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| 57 | |
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[932] | 58 | // ConstMap<Node, bool> const_true_map(true); |
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[869] | 59 | // This graph contains exaclty the tight edges. |
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[932] | 60 | // typedef SubGraphWrapper<Graph, ConstMap<Node, bool>, TightEdgeFilter> SubGW; |
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| 61 | typedef EdgeSubGraphWrapper<Graph, TightEdgeFilter> SubGW; |
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| 62 | SubGW gw(g, tight_edge_filter); |
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[866] | 63 | |
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| 64 | ConstMap<Edge, int> const_1_map(1); |
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| 65 | Graph::EdgeMap<int> flow(g, 0); |
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[869] | 66 | // Max flow between s and t in the graph of tight edges. |
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[866] | 67 | Preflow<SubGW, int, ConstMap<Edge, int>, Graph::EdgeMap<int> > |
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| 68 | preflow(gw, s, t, const_1_map, flow); |
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| 69 | preflow.run(); |
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| 70 | |
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[931] | 71 | cout << "maximum number of edge-disjoint shortest path: " |
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| 72 | << preflow.flowValue() << endl; |
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[866] | 73 | cout << "edges of the maximum number of edge-disjoint shortest s-t paths: " |
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| 74 | << endl; |
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| 75 | for(EdgeIt e(g); e!=INVALID; ++e) |
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| 76 | if (flow[e]) |
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[931] | 77 | cout << " " << g.id(e) << ", " |
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[986] | 78 | << g.id(g.source(e)) << "--" |
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| 79 | << length[e] << "->" << g.id(g.target(e)) << endl; |
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[866] | 80 | } |
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