src/work/marci/lp/max_flow_by_lp.cc
author alpar
Sat, 13 Nov 2004 12:53:28 +0000
changeset 986 e997802b855c
parent 921 818510fa3d99
child 1014 aae850a2394d
permissions -rw-r--r--
Naming changes:
- head -> target
- tail -> source
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// -*- c++ -*-
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#include <iostream>
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#include <fstream>
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#include <sage_graph.h>
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#include <lemon/smart_graph.h>
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#include <lemon/dimacs.h>
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#include <lemon/time_measure.h>
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//#include <graph_wrapper.h>
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#include <lemon/max_flow.h>
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#include <augmenting_flow.h>
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//#include <preflow_res.h>
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#include <for_each_macros.h>
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#include <lp_solver_wrapper.h>
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using namespace lemon;
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// Use a DIMACS max flow file as stdin.
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// max_flow_demo < dimacs_max_flow_file
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template<typename Edge, typename EdgeIndexMap> 
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class PrimalMap {
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protected:
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  LPSolverWrapper* lp;
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  EdgeIndexMap* edge_index_map;
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public:
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  PrimalMap(LPSolverWrapper& _lp, EdgeIndexMap& _edge_index_map) : 
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    lp(&_lp), edge_index_map(&_edge_index_map) { }
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  double operator[](Edge e) const { 
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    return lp->getPrimal((*edge_index_map)[e]);
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  }
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};
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int main(int, char **) {
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  typedef SageGraph MutableGraph;
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  //typedef SmartGraph Graph;
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  typedef SageGraph Graph;
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  typedef Graph::Node Node;
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  typedef Graph::EdgeIt EdgeIt;
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  Graph g;
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  Node s, t;
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  Graph::EdgeMap<int> cap(g);
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  //readDimacsMaxFlow(std::cin, g, s, t, cap);
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  readDimacs(std::cin, g, cap, s, t);
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  Timer ts;
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  Graph::EdgeMap<int> flow(g); //0 flow
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  MaxFlow<Graph, int, Graph::EdgeMap<int>, Graph::EdgeMap<int> > 
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    max_flow_test(g, s, t, cap, flow);
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  AugmentingFlow<Graph, int, Graph::EdgeMap<int>, Graph::EdgeMap<int> > 
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    augmenting_flow_test(g, s, t, cap, flow);
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  Graph::NodeMap<bool> cut(g);
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  {
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    std::cout << "preflow ..." << std::endl;
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    ts.reset();
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    max_flow_test.run();
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    std::cout << "elapsed time: " << ts << std::endl;
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    std::cout << "flow value: "<< max_flow_test.flowValue() << std::endl;
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    max_flow_test.actMinCut(cut);
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    FOR_EACH_LOC(Graph::EdgeIt, e, g) {
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      if (cut[g.source(e)] && !cut[g.target(e)] && !flow[e]==cap[e]) 
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	std::cout << "Slackness does not hold!" << std::endl;
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      if (!cut[g.source(e)] && cut[g.target(e)] && flow[e]>0) 
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	std::cout << "Slackness does not hold!" << std::endl;
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    }
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  }
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//   {
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//     std::cout << "preflow ..." << std::endl;
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//     FOR_EACH_LOC(Graph::EdgeIt, e, g) flow.set(e, 0);
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//     ts.reset();
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//     max_flow_test.preflow(MaxFlow<Graph, int, Graph::EdgeMap<int>, Graph::EdgeMap<int> >::GEN_FLOW);
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//     std::cout << "elapsed time: " << ts << std::endl;
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//     std::cout << "flow value: "<< max_flow_test.flowValue() << std::endl;
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//     FOR_EACH_LOC(Graph::EdgeIt, e, g) {
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//       if (cut[g.source(e)] && !cut[g.target(e)] && !flow[e]==cap[e]) 
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// 	std::cout << "Slackness does not hold!" << std::endl;
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//       if (!cut[g.source(e)] && cut[g.target(e)] && flow[e]>0) 
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// 	std::cout << "Slackness does not hold!" << std::endl;
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//     }
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//   }
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//   {
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//     std::cout << "wrapped preflow ..." << std::endl;
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//     FOR_EACH_LOC(Graph::EdgeIt, e, g) flow.set(e, 0);
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//     ts.reset();
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//     pre_flow_res.run();
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//     std::cout << "elapsed time: " << ts << std::endl;
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//     std::cout << "flow value: "<< pre_flow_test.flowValue() << std::endl;
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//   }
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  {
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    std::cout << "physical blocking flow augmentation ..." << std::endl;
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    FOR_EACH_LOC(Graph::EdgeIt, e, g) flow.set(e, 0);
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    ts.reset();
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    int i=0;
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    while (augmenting_flow_test.augmentOnBlockingFlow<MutableGraph>()) { ++i; }
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    std::cout << "elapsed time: " << ts << std::endl;
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    std::cout << "number of augmentation phases: " << i << std::endl; 
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    std::cout << "flow value: "<< augmenting_flow_test.flowValue() << std::endl;
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    FOR_EACH_LOC(Graph::EdgeIt, e, g) {
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      if (cut[g.source(e)] && !cut[g.target(e)] && !flow[e]==cap[e]) 
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	std::cout << "Slackness does not hold!" << std::endl;
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      if (!cut[g.source(e)] && cut[g.target(e)] && flow[e]>0) 
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	std::cout << "Slackness does not hold!" << std::endl;
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    }
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  }
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//   {
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//     std::cout << "faster physical blocking flow augmentation ..." << std::endl;
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//     FOR_EACH_LOC(Graph::EdgeIt, e, g) flow.set(e, 0);
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//     ts.reset();
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//     int i=0;
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//     while (max_flow_test.augmentOnBlockingFlow1<MutableGraph>()) { ++i; }
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//     std::cout << "elapsed time: " << ts << std::endl;
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//     std::cout << "number of augmentation phases: " << i << std::endl; 
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//     std::cout << "flow value: "<< max_flow_test.flowValue() << std::endl;
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//   }
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  {
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    std::cout << "on-the-fly blocking flow augmentation ..." << std::endl;
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    FOR_EACH_LOC(Graph::EdgeIt, e, g) flow.set(e, 0);
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    ts.reset();
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    int i=0;
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    while (augmenting_flow_test.augmentOnBlockingFlow2()) { ++i; }
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    std::cout << "elapsed time: " << ts << std::endl;
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    std::cout << "number of augmentation phases: " << i << std::endl; 
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    std::cout << "flow value: "<< augmenting_flow_test.flowValue() << std::endl;
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    FOR_EACH_LOC(Graph::EdgeIt, e, g) {
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      if (cut[g.source(e)] && !cut[g.target(e)] && !flow[e]==cap[e]) 
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	std::cout << "Slackness does not hold!" << std::endl;
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      if (!cut[g.source(e)] && cut[g.target(e)] && flow[e]>0) 
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	std::cout << "Slackness does not hold!" << std::endl;
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    }
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  }
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//   {
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//     std::cout << "on-the-fly shortest path augmentation ..." << std::endl;
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//     FOR_EACH_LOC(Graph::EdgeIt, e, g) flow.set(e, 0);
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//     ts.reset();
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//     int i=0;
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//     while (augmenting_flow_test.augmentOnShortestPath()) { ++i; }
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//     std::cout << "elapsed time: " << ts << std::endl;
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//     std::cout << "number of augmentation phases: " << i << std::endl; 
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//     std::cout << "flow value: "<< augmenting_flow_test.flowValue() << std::endl;
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//     FOR_EACH_LOC(Graph::EdgeIt, e, g) {
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//       if (cut[g.source(e)] && !cut[g.target(e)] && !flow[e]==cap[e]) 
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// 	std::cout << "Slackness does not hold!" << std::endl;
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//       if (!cut[g.source(e)] && cut[g.target(e)] && flow[e]>0) 
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// 	std::cout << "Slackness does not hold!" << std::endl;
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//     }
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//   }
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//   {
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//     std::cout << "on-the-fly shortest path augmentation ..." << std::endl;
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//     FOR_EACH_LOC(Graph::EdgeIt, e, g) flow.set(e, 0);
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//     ts.reset();
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//     int i=0;
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//     while (augmenting_flow_test.augmentOnShortestPath2()) { ++i; }
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//     std::cout << "elapsed time: " << ts << std::endl;
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//     std::cout << "number of augmentation phases: " << i << std::endl; 
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//     std::cout << "flow value: "<< augmenting_flow_test.flowValue() << std::endl;
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//     FOR_EACH_LOC(Graph::EdgeIt, e, g) {
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//       if (cut[g.source(e)] && !cut[g.target(e)] && !flow[e]==cap[e]) 
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// 	std::cout << "Slackness does not hold!" << std::endl;
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//       if (!cut[g.source(e)] && cut[g.target(e)] && flow[e]>0) 
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// 	std::cout << "Slackness does not hold!" << std::endl;
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//     }
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//   }
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  ts.reset();
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  LPSolverWrapper lp;
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  lp.setMaximize();
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  typedef LPSolverWrapper::ColIt ColIt;
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  typedef LPSolverWrapper::RowIt RowIt;
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  typedef Graph::EdgeMap<ColIt> EdgeIndexMap;
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  EdgeIndexMap edge_index_map(g);
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  PrimalMap<Graph::Edge, EdgeIndexMap> lp_flow(lp, edge_index_map);
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  Graph::EdgeIt e;
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  for (g.first(e); g.valid(e); g.next(e)) {
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    ColIt col_it=lp.addCol();
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    edge_index_map.set(e, col_it);
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    lp.setColBounds(col_it, LPX_DB, 0.0, cap[e]);
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  }
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  Graph::NodeIt n;
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  for (g.first(n); g.valid(n); g.next(n)) {
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    if (n!=s) {
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      //hurokelek miatt
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      Graph::EdgeMap<int> coeffs(g, 0);
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      {
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	Graph::InEdgeIt e;
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	for (g.first(e, n); g.valid(e); g.next(e)) coeffs.set(e, coeffs[e]+1);
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      }
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      {
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	Graph::OutEdgeIt e;
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	for (g.first(e, n); g.valid(e); g.next(e)) coeffs.set(e, coeffs[e]-1);
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      }
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      if (n==t) {
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	Graph::EdgeIt e;
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	//std::vector< std::pair<ColIt, double> > row;
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	for (g.first(e); g.valid(e); g.next(e)) {
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	  if (coeffs[e]!=0) 
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	    lp.setObjCoef(edge_index_map[e], coeffs[e]);
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	}
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      } else  {
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	RowIt row_it=lp.addRow();
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	Graph::EdgeIt e;
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	std::vector< std::pair<ColIt, double> > row;
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	for (g.first(e); g.valid(e); g.next(e)) {
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	  if (coeffs[e]!=0) 
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	    row.push_back(std::make_pair(edge_index_map[e], coeffs[e]));
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	}	
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	lp.setRowCoeffs(row_it, row.begin(), row.end());
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	lp.setRowBounds(row_it, LPX_FX, 0.0, 0.0);
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      }
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    }
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  }
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  lp.solveSimplex();
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  std::cout << "flow value: "<< lp.getObjVal() << std::endl;
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  std::cout << "elapsed time: " << ts << std::endl;
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  return 0;
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}