90 lines
3.2 KiB
C++
90 lines
3.2 KiB
C++
// Copyright 2010-2014 Google
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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//
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// Integer programming example that shows how to use the API.
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#include "base/commandlineflags.h"
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#include "base/logging.h"
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#include "linear_solver/linear_solver.h"
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namespace operations_research {
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void RunIntegerProgrammingExample(
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MPSolver::OptimizationProblemType optimization_problem_type) {
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MPSolver solver("IntegerProgrammingExample", optimization_problem_type);
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const double infinity = solver.infinity();
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// x1 and x2 are integer non-negative variables.
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MPVariable* const x1 = solver.MakeIntVar(0.0, infinity, "x1");
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MPVariable* const x2 = solver.MakeIntVar(0.0, infinity, "x2");
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// Minimize x1 + 2 * x2.
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MPObjective* const objective = solver.MutableObjective();
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objective->SetCoefficient(x1, 1);
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objective->SetCoefficient(x2, 2);
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// 2 * x2 + 3 * x1 >= 17.
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MPConstraint* const c0 = solver.MakeRowConstraint(17, infinity);
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c0->SetCoefficient(x1, 3);
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c0->SetCoefficient(x2, 2);
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const MPSolver::ResultStatus result_status = solver.Solve();
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// Check that the problem has an optimal solution.
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if (result_status != MPSolver::OPTIMAL) {
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LOG(FATAL) << "The problem does not have an optimal solution!";
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}
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LOG(INFO) << "Problem solved in " << solver.wall_time() << " milliseconds";
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// The objective value of the solution.
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LOG(INFO) << "Optimal objective value = " << objective->Value();
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// The value of each variable in the solution.
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LOG(INFO) << "x1 = " << x1->solution_value();
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LOG(INFO) << "x2 = " << x2->solution_value();
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LOG(INFO) << "Advanced usage:";
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LOG(INFO) << "Problem solved in " << solver.nodes()
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<< " branch-and-bound nodes";
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}
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void RunAllExamples() {
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#if defined(USE_GLPK)
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LOG(INFO) << "---- Integer programming example with GLPK ----";
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RunIntegerProgrammingExample(MPSolver::GLPK_MIXED_INTEGER_PROGRAMMING);
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#endif
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#if defined(USE_CBC)
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LOG(INFO) << "---- Integer programming example with CBC ----";
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RunIntegerProgrammingExample(MPSolver::CBC_MIXED_INTEGER_PROGRAMMING);
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#endif
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#if defined(USE_SCIP)
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LOG(INFO) << "---- Integer programming example with SCIP ----";
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RunIntegerProgrammingExample(MPSolver::SCIP_MIXED_INTEGER_PROGRAMMING);
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#endif
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#if defined(USE_GUROBI)
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LOG(INFO) << "---- Integer programming example with Gurobi ----";
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RunIntegerProgrammingExample(MPSolver::GUROBI_MIXED_INTEGER_PROGRAMMING);
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#endif // USE_GUROBI
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#if defined(USE_CPLEX)
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LOG(INFO) << "---- Integer programming example with CPLEX ----";
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RunIntegerProgrammingExample(MPSolver::CPLEX_MIXED_INTEGER_PROGRAMMING);
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#endif // USE_CPLEX
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}
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} // namespace operations_research
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int main(int argc, char** argv) {
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google::ParseCommandLineFlags( &argc, &argv, true);
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operations_research::RunAllExamples();
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return 0;
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}
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