source: lemon-0.x/src/work/marci/lp/max_flow_by_lp.cc @ 1031:0b7169db694f

// -*- c++ -*-
#include <iostream>
#include <fstream>

#include <lemon/smart_graph.h>
#include <lemon/list_graph.h>
#include <lemon/dimacs.h>
#include <lemon/time_measure.h>
//#include <graph_wrapper.h>
#include <lemon/preflow.h>
#include <augmenting_flow.h>
//#include <preflow_res.h>
//#include <lp_solver_wrapper_2.h>
#include <min_cost_gen_flow.h>

// Use a DIMACS max flow file as stdin.
// max_flow_demo < dimacs_max_flow_file

using namespace lemon;

int main(int, char **) {

  typedef ListGraph MutableGraph;
  typedef ListGraph Graph;
  typedef Graph::Node Node;
  typedef Graph::Edge Edge;
  typedef Graph::EdgeIt EdgeIt;

  Graph g;

  Node s, t;
  Graph::EdgeMap<int> cap(g);
  //readDimacsMaxFlow(std::cin, g, s, t, cap);
  readDimacs(std::cin, g, cap, s, t);
  Timer ts;
  Graph::EdgeMap<int> flow(g); //0 flow
  Preflow<Graph, int, Graph::EdgeMap<int>, Graph::EdgeMap<int> > 
    max_flow_test(g, s, t, cap, flow);
  AugmentingFlow<Graph, int, Graph::EdgeMap<int>, Graph::EdgeMap<int> > 
    augmenting_flow_test(g, s, t, cap, flow);
  
  Graph::NodeMap<bool> cut(g);

  {
    std::cout << "preflow ..." << std::endl;
    ts.reset();
    max_flow_test.run();
    std::cout << "elapsed time: " << ts << std::endl;
    std::cout << "flow value: "<< max_flow_test.flowValue() << std::endl;
    max_flow_test.minCut(cut);

    for (EdgeIt e(g); e!=INVALID; ++e) {
      if (cut[g.source(e)] && !cut[g.target(e)] && !flow[e]==cap[e]) 
        std::cout << "Slackness does not hold!" << std::endl;
      if (!cut[g.source(e)] && cut[g.target(e)] && flow[e]>0) 
        std::cout << "Slackness does not hold!" << std::endl;
    }
  }

//   {
//     std::cout << "preflow ..." << std::endl;
//     FOR_EACH_LOC(Graph::EdgeIt, e, g) flow.set(e, 0);
//     ts.reset();
//     max_flow_test.preflow(Preflow<Graph, int, Graph::EdgeMap<int>, Graph::EdgeMap<int> >::GEN_FLOW);
//     std::cout << "elapsed time: " << ts << std::endl;
//     std::cout << "flow value: "<< max_flow_test.flowValue() << std::endl;

//     FOR_EACH_LOC(Graph::EdgeIt, e, g) {
//       if (cut[g.source(e)] && !cut[g.target(e)] && !flow[e]==cap[e]) 
//      std::cout << "Slackness does not hold!" << std::endl;
//       if (!cut[g.source(e)] && cut[g.target(e)] && flow[e]>0) 
//      std::cout << "Slackness does not hold!" << std::endl;
//     }
//   }

//   {
//     std::cout << "wrapped preflow ..." << std::endl;
//     FOR_EACH_LOC(Graph::EdgeIt, e, g) flow.set(e, 0);
//     ts.reset();
//     pre_flow_res.run();
//     std::cout << "elapsed time: " << ts << std::endl;
//     std::cout << "flow value: "<< pre_flow_test.flowValue() << std::endl;
//   }

  {
    std::cout << "physical blocking flow augmentation ..." << std::endl;
    for (EdgeIt e(g); e!=INVALID; ++e) flow.set(e, 0);
    ts.reset();
    int i=0;
    while (augmenting_flow_test.augmentOnBlockingFlow<MutableGraph>()) { ++i; }
    std::cout << "elapsed time: " << ts << std::endl;
    std::cout << "number of augmentation phases: " << i << std::endl; 
    std::cout << "flow value: "<< augmenting_flow_test.flowValue() << std::endl;

    for (EdgeIt e(g); e!=INVALID; ++e) {
      if (cut[g.source(e)] && !cut[g.target(e)] && !flow[e]==cap[e]) 
        std::cout << "Slackness does not hold!" << std::endl;
      if (!cut[g.source(e)] && cut[g.target(e)] && flow[e]>0) 
        std::cout << "Slackness does not hold!" << std::endl;
    }
  }

//   {
//     std::cout << "faster physical blocking flow augmentation ..." << std::endl;
//     FOR_EACH_LOC(Graph::EdgeIt, e, g) flow.set(e, 0);
//     ts.reset();
//     int i=0;
//     while (max_flow_test.augmentOnBlockingFlow1<MutableGraph>()) { ++i; }
//     std::cout << "elapsed time: " << ts << std::endl;
//     std::cout << "number of augmentation phases: " << i << std::endl; 
//     std::cout << "flow value: "<< max_flow_test.flowValue() << std::endl;
//   }

  {
    std::cout << "on-the-fly blocking flow augmentation ..." << std::endl;
    for (EdgeIt e(g); e!=INVALID; ++e) flow.set(e, 0);
    ts.reset();
    int i=0;
    while (augmenting_flow_test.augmentOnBlockingFlow2()) { ++i; }
    std::cout << "elapsed time: " << ts << std::endl;
    std::cout << "number of augmentation phases: " << i << std::endl; 
    std::cout << "flow value: "<< augmenting_flow_test.flowValue() << std::endl;

    for (EdgeIt e(g); e!=INVALID; ++e) {
      if (cut[g.source(e)] && !cut[g.target(e)] && !flow[e]==cap[e]) 
        std::cout << "Slackness does not hold!" << std::endl;
      if (!cut[g.source(e)] && cut[g.target(e)] && flow[e]>0) 
        std::cout << "Slackness does not hold!" << std::endl;
    }
  }

//   {
//     std::cout << "on-the-fly shortest path augmentation ..." << std::endl;
//     FOR_EACH_LOC(Graph::EdgeIt, e, g) flow.set(e, 0);
//     ts.reset();
//     int i=0;
//     while (augmenting_flow_test.augmentOnShortestPath()) { ++i; }
//     std::cout << "elapsed time: " << ts << std::endl;
//     std::cout << "number of augmentation phases: " << i << std::endl; 
//     std::cout << "flow value: "<< augmenting_flow_test.flowValue() << std::endl;

//     FOR_EACH_LOC(Graph::EdgeIt, e, g) {
//       if (cut[g.source(e)] && !cut[g.target(e)] && !flow[e]==cap[e]) 
//      std::cout << "Slackness does not hold!" << std::endl;
//       if (!cut[g.source(e)] && cut[g.target(e)] && flow[e]>0) 
//      std::cout << "Slackness does not hold!" << std::endl;
//     }
//   }

//   {
//     std::cout << "on-the-fly shortest path augmentation ..." << std::endl;
//     FOR_EACH_LOC(Graph::EdgeIt, e, g) flow.set(e, 0);
//     ts.reset();
//     int i=0;
//     while (augmenting_flow_test.augmentOnShortestPath2()) { ++i; }
//     std::cout << "elapsed time: " << ts << std::endl;
//     std::cout << "number of augmentation phases: " << i << std::endl; 
//     std::cout << "flow value: "<< augmenting_flow_test.flowValue() << std::endl;

//     FOR_EACH_LOC(Graph::EdgeIt, e, g) {
//       if (cut[g.source(e)] && !cut[g.target(e)] && !flow[e]==cap[e]) 
//      std::cout << "Slackness does not hold!" << std::endl;
//       if (!cut[g.source(e)] && cut[g.target(e)] && flow[e]>0) 
//      std::cout << "Slackness does not hold!" << std::endl;
//     }
//   }

  ts.reset();

  Edge e=g.addEdge(t, s);
  Graph::EdgeMap<int> cost(g, 0);
  cost.set(e, -1);
  cap.set(e, 10000);
  typedef ConstMap<Node, int> Excess;
  Excess excess(0);
  typedef ConstMap<Edge, int> LCap;
  LCap lcap(0);

  MinCostGenFlow<Graph, int, Excess, LCap> 
    min_cost(g, excess, lcap, cap, flow, cost); 
  min_cost.feasible();
  min_cost.runByLP();

  std::cout << "elapsed time: " << ts << std::endl;
  std::cout << "flow value: "<< flow[e] << std::endl;
}