/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Copyright (C) 2003-2010

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */

///\file

///\brief Demo program for the MIP solver interface.

///

/// This demo program shows how the LEMON MIP solver interface can be used.

/// A simple mixed integer programming (MIP) problem is formulated and solved

/// using the default MIP solver (e.g. GLPK).

///

/// \include mip_demo.cc

#include <iostream>

#include <lemon/lp.h>

using namespace lemon;

int main()

{

  // Create an instance of the default MIP solver class

  // (it will represent an "empty" problem at first)

  Mip mip;

  // Add two columns (variables) to the problem

  Mip::Col x1 = mip.addCol();

  Mip::Col x2 = mip.addCol();

  // Add rows (constraints) to the problem

  mip.addRow(x1 - 5 <= x2);

  mip.addRow(0 <= 2 * x1 + x2 <= 25);

  // Set lower and upper bounds for the columns (variables)

  mip.colLowerBound(x1, 0);

  mip.colUpperBound(x2, 10);

  // Set the type of the columns

  mip.colType(x1, Mip::INTEGER);

  mip.colType(x2, Mip::REAL);

  // Specify the objective function

  mip.max();

  mip.obj(5 * x1 + 3 * x2);

  // Solve the problem using the underlying MIP solver

  mip.solve();

  // Print the results

  if (mip.type() == Mip::OPTIMAL) {

    std::cout << "Objective function value: " << mip.solValue() << std::endl;

    std::cout << "x1 = " << mip.sol(x1) << std::endl;

    std::cout << "x2 = " << mip.sol(x2) << std::endl;

  } else {

    std::cout << "Optimal solution not found." << std::endl;

  }

  return 0;

}