/* -*- 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;

 }