/* -*- 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 LP solver interface.

///

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

/// A simple linear programming (LP) problem is formulated and solved using

/// the default LP solver (e.g. GLPK).

///

/// \include lp_demo.cc

#include <iostream>

#include <lemon/lp.h>

using namespace lemon;

int main()

{

  // Create an instance of the default LP solver class

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

  Lp lp;

  // Add two columns (variables) to the problem

  Lp::Col x1 = lp.addCol();

  Lp::Col x2 = lp.addCol();

  // Add rows (constraints) to the problem

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

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

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

  lp.colLowerBound(x1, 0);

  lp.colUpperBound(x2, 10);

  // Specify the objective function

  lp.max();

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

  // Solve the problem using the underlying LP solver

  lp.solve();

  // Print the results

  if (lp.primalType() == Lp::OPTIMAL) {

    std::cout << "Objective function value: " << lp.primal() << std::endl;

    std::cout << "x1 = " << lp.primal(x1) << std::endl;

    std::cout << "x2 = " << lp.primal(x2) << std::endl;

  } else {

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

  }

  return 0;

}