demo/lgf_demo.cc
author Peter Kovacs <kpeter@inf.elte.hu>
Fri, 17 Apr 2009 18:04:36 +0200
changeset 609 e6927fe719e6
parent 294 cbe3ec2d59d2
permissions -rw-r--r--
Support >= and <= constraints in NetworkSimplex (#219, #234)

By default the same inequality constraints are supported as by
Circulation (the GEQ form), but the LEQ form can also be selected
using the problemType() function.

The documentation of the min. cost flow module is reworked and
extended with important notes and explanations about the different
variants of the problem and about the dual solution and optimality
conditions.
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/* -*- mode: C++; indent-tabs-mode: nil; -*-
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 *
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 * This file is a part of LEMON, a generic C++ optimization library.
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 *
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 * Copyright (C) 2003-2009
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 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
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 * (Egervary Research Group on Combinatorial Optimization, EGRES).
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 *
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 * Permission to use, modify and distribute this software is granted
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 * provided that this copyright notice appears in all copies. For
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 * precise terms see the accompanying LICENSE file.
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 *
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 * This software is provided "AS IS" with no warranty of any kind,
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 * express or implied, and with no claim as to its suitability for any
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 * purpose.
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 *
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 */
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///\ingroup demos
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///\file
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///\brief Demonstrating graph input and output
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///
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/// This program gives an example of how to read and write a digraph
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/// and additional maps from/to a stream or a file using the
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/// \ref lgf-format "LGF" format.
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///
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/// The \c "digraph.lgf" file:
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/// \include digraph.lgf
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///
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/// And the program which reads it and prints the digraph to the
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/// standard output:
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/// \include lgf_demo.cc
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#include <iostream>
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#include <lemon/smart_graph.h>
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#include <lemon/lgf_reader.h>
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#include <lemon/lgf_writer.h>
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using namespace lemon;
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int main() {
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  SmartDigraph g;
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  SmartDigraph::ArcMap<int> cap(g);
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  SmartDigraph::Node s, t;
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  try {
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    digraphReader(g, "digraph.lgf"). // read the directed graph into g
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      arcMap("capacity", cap).       // read the 'capacity' arc map into cap
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      node("source", s).             // read 'source' node to s
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      node("target", t).             // read 'target' node to t
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      run();
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  } catch (Exception& error) { // check if there was any error
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    std::cerr << "Error: " << error.what() << std::endl;
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    return -1;
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  }
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  std::cout << "A digraph is read from 'digraph.lgf'." << std::endl;
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  std::cout << "Number of nodes: " << countNodes(g) << std::endl;
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  std::cout << "Number of arcs: " << countArcs(g) << std::endl;
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  std::cout << "We can write it to the standard output:" << std::endl;
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  digraphWriter(g).                // write g to the standard output
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    arcMap("capacity", cap).       // write cap into 'capacity'
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    node("source", s).             // write s to 'source'
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    node("target", t).             // write t to 'target'
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    run();
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  return 0;
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}