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

2 | * |
---|

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

4 | * |
---|

5 | * Copyright (C) 2003-2010 |
---|

6 | * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
---|

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

8 | * |
---|

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

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

11 | * precise terms see the accompanying LICENSE file. |
---|

12 | * |
---|

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

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

15 | * purpose. |
---|

16 | * |
---|

17 | */ |
---|

18 | |
---|

19 | ///\file |
---|

20 | ///\brief Demo program for the MIP solver interface. |
---|

21 | /// |
---|

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

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

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

25 | /// |
---|

26 | /// \include mip_demo.cc |
---|

27 | |
---|

28 | #include <iostream> |
---|

29 | #include <lemon/lp.h> |
---|

30 | |
---|

31 | using namespace lemon; |
---|

32 | |
---|

33 | int main() |
---|

34 | { |
---|

35 | // Create an instance of the default MIP solver class |
---|

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

37 | Mip mip; |
---|

38 | |
---|

39 | // Add two columns (variables) to the problem |
---|

40 | Mip::Col x1 = mip.addCol(); |
---|

41 | Mip::Col x2 = mip.addCol(); |
---|

42 | |
---|

43 | // Add rows (constraints) to the problem |
---|

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

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

46 | |
---|

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

48 | mip.colLowerBound(x1, 0); |
---|

49 | mip.colUpperBound(x2, 10); |
---|

50 | |
---|

51 | // Set the type of the columns |
---|

52 | mip.colType(x1, Mip::INTEGER); |
---|

53 | mip.colType(x2, Mip::REAL); |
---|

54 | |
---|

55 | // Specify the objective function |
---|

56 | mip.max(); |
---|

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

58 | |
---|

59 | // Solve the problem using the underlying MIP solver |
---|

60 | mip.solve(); |
---|

61 | |
---|

62 | // Print the results |
---|

63 | if (mip.type() == Mip::OPTIMAL) { |
---|

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

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

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

67 | } else { |
---|

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

69 | } |
---|

70 | |
---|

71 | return 0; |
---|

72 | } |
---|