OR-Tools  8.2
simple_glop_program.cc
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1 // Copyright 2010-2018 Google LLC
2 // Licensed under the Apache License, Version 2.0 (the "License");
3 // you may not use this file except in compliance with the License.
4 // You may obtain a copy of the License at
5 //
6 // http://www.apache.org/licenses/LICENSE-2.0
7 //
8 // Unless required by applicable law or agreed to in writing, software
9 // distributed under the License is distributed on an "AS IS" BASIS,
10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11 // See the License for the specific language governing permissions and
12 // limitations under the License.
13 
14 // Minimal example to call the GLOP solver.
15 // [START program]
16 // [START import]
17 #include <iostream>
18 
19 #include "ortools/glop/lp_solver.h"
22 // [END import]
23 
24 namespace operations_research::glop {
26  LinearProgram lp;
27  // Create the variables x and y.
28  ColIndex col_x = lp.FindOrCreateVariable("x");
29  lp.SetVariableBounds(col_x, 0.0, 1.0);
30  ColIndex col_y = lp.FindOrCreateVariable("y");
31  lp.SetVariableBounds(col_y, 0.0, 2.0);
32 
33  // Create linear constraint: 0 <= x + y <= 2.
34  RowIndex row_r1 = lp.FindOrCreateConstraint("r1");
35  lp.SetConstraintBounds(row_r1, 0.0, 2.0);
36  lp.SetCoefficient(row_r1, col_x, 1);
37  lp.SetCoefficient(row_r1, col_y, 1);
38 
39  // Create objective function: 3 * x + y.
40  lp.SetObjectiveCoefficient(col_x, 3);
41  lp.SetObjectiveCoefficient(col_y, 1);
42  lp.SetMaximizationProblem(true);
43 
44  lp.CleanUp();
45 
46  std::cout << "Number of variables = " << lp.num_variables() << std::endl;
47  std::cout << "Number of constraints = " << lp.num_constraints() << std::endl;
48 
49  LPSolver solver;
50  GlopParameters parameters;
51  parameters.set_provide_strong_optimal_guarantee(true);
52  solver.SetParameters(parameters);
53 
54  ProblemStatus status = solver.Solve(lp);
55  if (status == ProblemStatus::OPTIMAL) {
56  std::cout << "Optimal solution found !" << std::endl;
57  // The objective value of the solution.
58  std::cout << "Optimal objective value = " << solver.GetObjectiveValue()
59  << std::endl;
60  // The value of each variable in the solution.
61  const DenseRow& values = solver.variable_values();
62  std::cout << "Solution:" << std::endl
63  << "x = " << values[col_x] << std::endl
64  << ", y = " << values[col_y] << std::endl;
65  return EXIT_SUCCESS;
66  } else {
67  return EXIT_FAILURE;
68  }
69 }
70 } // namespace operations_research::glop
71 
72 int main(int argc, char** argv) {
74 }
75 // [END program]
const DenseRow & variable_values() const
Definition: lp_solver.h:100
Fractional GetObjectiveValue() const
Definition: lp_solver.cc:476
ABSL_MUST_USE_RESULT ProblemStatus Solve(const LinearProgram &lp)
Definition: lp_solver.cc:121
void SetParameters(const GlopParameters &parameters)
Definition: lp_solver.cc:113
void SetVariableBounds(ColIndex col, Fractional lower_bound, Fractional upper_bound)
Definition: lp_data.cc:248
void SetCoefficient(RowIndex row, ColIndex col, Fractional value)
Definition: lp_data.cc:316
ColIndex FindOrCreateVariable(const std::string &variable_id)
Definition: lp_data.cc:204
void SetConstraintBounds(RowIndex row, Fractional lower_bound, Fractional upper_bound)
Definition: lp_data.cc:308
RowIndex FindOrCreateConstraint(const std::string &constraint_id)
Definition: lp_data.cc:217
void SetObjectiveCoefficient(ColIndex col, Fractional value)
Definition: lp_data.cc:325
void SetMaximizationProblem(bool maximize)
Definition: lp_data.cc:342
SatParameters parameters
int main(int argc, char **argv)