[1104] | 1 | // -*- c++ -*- |
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| 2 | #include <iostream> |
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| 3 | #include <fstream> |
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| 4 | |
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[1143] | 5 | #include <lemon/graph_utils.h> |
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[1104] | 6 | #include <lemon/smart_graph.h> |
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| 7 | #include <lemon/list_graph.h> |
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| 8 | #include <lemon/dimacs.h> |
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| 9 | #include <lemon/time_measure.h> |
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[1241] | 10 | #include <lp_solver_glpk.h> |
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[1104] | 11 | |
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| 12 | using std::cout; |
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| 13 | using std::endl; |
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| 14 | using namespace lemon; |
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| 15 | |
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| 16 | template<typename Edge, typename EdgeIndexMap> |
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| 17 | class PrimalMap { |
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| 18 | protected: |
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[1241] | 19 | LpGlpk* lp; |
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[1104] | 20 | EdgeIndexMap* edge_index_map; |
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| 21 | public: |
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[1241] | 22 | PrimalMap(LpGlpk& _lp, EdgeIndexMap& _edge_index_map) : |
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[1104] | 23 | lp(&_lp), edge_index_map(&_edge_index_map) { } |
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| 24 | double operator[](Edge e) const { |
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| 25 | return lp->getPrimal((*edge_index_map)[e]); |
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| 26 | } |
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| 27 | }; |
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| 28 | |
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| 29 | // Use a DIMACS max flow file as stdin. |
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| 30 | // max_flow_expresion < dimacs_max_flow_file |
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| 31 | |
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| 32 | int main(int, char **) { |
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| 33 | |
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| 34 | typedef ListGraph Graph; |
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| 35 | typedef Graph::Node Node; |
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| 36 | typedef Graph::Edge Edge; |
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| 37 | typedef Graph::EdgeIt EdgeIt; |
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| 38 | |
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| 39 | Graph g; |
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| 40 | |
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| 41 | Node s, t; |
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| 42 | Graph::EdgeMap<int> cap(g); |
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| 43 | readDimacs(std::cin, g, cap, s, t); |
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| 44 | Timer ts; |
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| 45 | |
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[1241] | 46 | typedef LpGlpk LPSolver; |
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[1104] | 47 | LPSolver lp; |
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| 48 | lp.setMaximize(); |
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[1144] | 49 | typedef LPSolver::Col Col; |
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| 50 | typedef LPSolver::Row Row; |
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| 51 | typedef Graph::EdgeMap<Col> EdgeIndexMap; |
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| 52 | typedef Graph::NodeMap<Row> NodeIndexMap; |
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[1104] | 53 | EdgeIndexMap edge_index_map(g); |
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[1143] | 54 | NodeIndexMap node_index_map(g); |
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[1110] | 55 | PrimalMap<Edge, EdgeIndexMap> flow(lp, edge_index_map); |
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[1104] | 56 | |
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[1111] | 57 | // nonnegativity of flow and capacity function |
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[1104] | 58 | for (Graph::EdgeIt e(g); e!=INVALID; ++e) { |
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[1144] | 59 | Col col=lp.addCol(); |
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| 60 | edge_index_map.set(e, col); |
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[1110] | 61 | // interesting property in GLPK: |
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| 62 | // if you change the order of the following two lines, the |
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| 63 | // two runs of GLPK are extremely different |
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[1144] | 64 | lp.setColLowerBound(col, 0); |
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| 65 | lp.setColUpperBound(col, cap[e]); |
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[1104] | 66 | } |
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| 67 | |
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| 68 | for (Graph::NodeIt n(g); n!=INVALID; ++n) { |
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| 69 | LPSolver::Expression expr; |
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| 70 | for (Graph::OutEdgeIt e(g, n); e!=INVALID; ++e) |
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| 71 | expr+=edge_index_map[e]; |
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| 72 | for (Graph::InEdgeIt e(g, n); e!=INVALID; ++e) |
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| 73 | expr-=edge_index_map[e]; |
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| 74 | // cost function |
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| 75 | if (n==s) { |
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| 76 | lp.setObjCoeffs(expr); |
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| 77 | } |
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[1111] | 78 | // flow conservation constraints |
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[1104] | 79 | if ((n!=s) && (n!=t)) { |
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[1144] | 80 | node_index_map.set(n, lp.addRow(expr == 0.0)); |
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[1104] | 81 | } |
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| 82 | } |
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| 83 | lp.solveSimplex(); |
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[1110] | 84 | cout << "elapsed time: " << ts << endl; |
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[1152] | 85 | // cout << "rows:" << endl; |
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| 86 | // for ( |
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| 87 | // LPSolver::Rows::ClassIt i(lp.row_iter_map, 0); |
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| 88 | // i!=INVALID; |
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| 89 | // ++i) { |
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| 90 | // cout << i << " "; |
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| 91 | // } |
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| 92 | // cout << endl; |
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| 93 | // cout << "cols:" << endl; |
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| 94 | // for ( |
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| 95 | // LPSolver::Cols::ClassIt i(lp.col_iter_map, 0); |
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| 96 | // i!=INVALID; |
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| 97 | // ++i) { |
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| 98 | // cout << i << " "; |
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| 99 | // } |
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| 100 | // cout << endl; |
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| 101 | lp.setMIP(); |
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| 102 | cout << "elapsed time: " << ts << endl; |
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| 103 | for (LPSolver::Cols::ClassIt it(lp.col_iter_map ,1); it!=INVALID; ++it) { |
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| 104 | lp.setColInt(it); |
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| 105 | } |
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| 106 | cout << "elapsed time: " << ts << endl; |
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| 107 | lp.solveBandB(); |
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| 108 | cout << "elapsed time: " << ts << endl; |
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[1104] | 109 | } |
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