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1 /* -*- mode: C++; indent-tabs-mode: nil; -*- |
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2 * |
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3 * This file is a part of LEMON, a generic C++ optimization library. |
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4 * |
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5 * Copyright (C) 2003-2010 |
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6 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport |
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7 * (Egervary Research Group on Combinatorial Optimization, EGRES). |
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8 * |
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9 * Permission to use, modify and distribute this software is granted |
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10 * provided that this copyright notice appears in all copies. For |
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11 * precise terms see the accompanying LICENSE file. |
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12 * |
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13 * This software is provided "AS IS" with no warranty of any kind, |
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14 * express or implied, and with no claim as to its suitability for any |
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15 * purpose. |
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16 * |
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17 */ |
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18 |
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19 ///\file |
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20 ///\brief Demo program for the MIP solver interface. |
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21 /// |
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22 /// This demo program shows how the LEMON MIP solver interface can be used. |
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23 /// A simple mixed integer programming (MIP) problem is formulated and solved |
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24 /// using the default MIP solver (e.g. GLPK). |
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25 /// |
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26 /// \include mip_demo.cc |
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27 |
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28 #include <iostream> |
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29 #include <lemon/lp.h> |
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30 |
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31 using namespace lemon; |
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32 |
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33 int main() |
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34 { |
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35 // Create an instance of the default MIP solver class |
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36 // (it will represent an "empty" problem at first) |
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37 Mip mip; |
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38 |
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39 // Add two columns (variables) to the problem |
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40 Mip::Col x1 = mip.addCol(); |
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41 Mip::Col x2 = mip.addCol(); |
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42 |
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43 // Add rows (constraints) to the problem |
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44 mip.addRow(x1 - 5 <= x2); |
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45 mip.addRow(0 <= 2 * x1 + x2 <= 25); |
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46 |
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47 // Set lower and upper bounds for the columns (variables) |
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48 mip.colLowerBound(x1, 0); |
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49 mip.colUpperBound(x2, 10); |
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50 |
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51 // Set the type of the columns |
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52 mip.colType(x1, Mip::INTEGER); |
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53 mip.colType(x2, Mip::REAL); |
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54 |
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55 // Specify the objective function |
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56 mip.max(); |
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57 mip.obj(5 * x1 + 3 * x2); |
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58 |
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59 // Solve the problem using the underlying MIP solver |
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60 mip.solve(); |
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61 |
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62 // Print the results |
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63 if (mip.type() == Mip::OPTIMAL) { |
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64 std::cout << "Objective function value: " << mip.solValue() << std::endl; |
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65 std::cout << "x1 = " << mip.sol(x1) << std::endl; |
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66 std::cout << "x2 = " << mip.sol(x2) << std::endl; |
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67 } else { |
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68 std::cout << "Optimal solution not found." << std::endl; |
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69 } |
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70 |
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71 return 0; |
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72 } |