Boost C++ Libraries

libs/graph/example/edmonds-karp-eg.cpp

//=======================================================================
// Copyright 2001 Jeremy G. Siek, Andrew Lumsdaine, Lie-Quan Lee, 
//
// Distributed under the Boost Software License, Version 1.0. (See
// accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//=======================================================================

#ifdef _MSC_VER
#define _CRT_SECURE_NO_WARNINGS
#endif

#include <boost/config.hpp>
#include <iostream>
#include <string>
#include <boost/graph/edmonds_karp_max_flow.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/read_dimacs.hpp>
#include <boost/graph/graph_utility.hpp>

// Use a DIMACS network flow file as stdin.
// edmonds-karp-eg < max_flow.dat
//
// Sample output:
//  c  The total flow:
//  s 13
//
//  c flow values:
//  f 0 6 3
//  f 0 1 6
//  f 0 2 4
//  f 1 5 1
//  f 1 0 0
//  f 1 3 5
//  f 2 4 4
//  f 2 3 0
//  f 2 0 0
//  f 3 7 5
//  f 3 2 0
//  f 3 1 0
//  f 4 5 4
//  f 4 6 0
//  f 5 4 0
//  f 5 7 5
//  f 6 7 3
//  f 6 4 0
//  f 7 6 0
//  f 7 5 0

int
main()
{
  using namespace boost;

  typedef adjacency_list_traits < vecS, vecS, directedS > Traits;
  typedef adjacency_list < listS, vecS, directedS,
    property < vertex_name_t, std::string >,
    property < edge_capacity_t, long,
    property < edge_residual_capacity_t, long,
    property < edge_reverse_t, Traits::edge_descriptor > > > > Graph;

  Graph g;

  property_map < Graph, edge_capacity_t >::type
    capacity = get(edge_capacity, g);
  property_map < Graph, edge_reverse_t >::type rev = get(edge_reverse, g);
  property_map < Graph, edge_residual_capacity_t >::type
    residual_capacity = get(edge_residual_capacity, g);

  Traits::vertex_descriptor s, t;
  read_dimacs_max_flow(g, capacity, rev, s, t);

#if defined(BOOST_MSVC) && BOOST_MSVC <= 1300
  std::vector<default_color_type> color(num_vertices(g));
  std::vector<Traits::edge_descriptor> pred(num_vertices(g));
  long flow = edmonds_karp_max_flow
    (g, s, t, capacity, residual_capacity, rev, &color[0], &pred[0]);
#else
  long flow = edmonds_karp_max_flow(g, s, t);
#endif

  std::cout << "c  The total flow:" << std::endl;
  std::cout << "s " << flow << std::endl << std::endl;

  std::cout << "c flow values:" << std::endl;
  graph_traits < Graph >::vertex_iterator u_iter, u_end;
  graph_traits < Graph >::out_edge_iterator ei, e_end;
  for (boost::tie(u_iter, u_end) = vertices(g); u_iter != u_end; ++u_iter)
    for (boost::tie(ei, e_end) = out_edges(*u_iter, g); ei != e_end; ++ei)
      if (capacity[*ei] > 0)
        std::cout << "f " << *u_iter << " " << target(*ei, g) << " "
          << (capacity[*ei] - residual_capacity[*ei]) << std::endl;

  return EXIT_SUCCESS;
}