72 lines
2.4 KiB
C++
72 lines
2.4 KiB
C++
// Copyright 2010-2021 Google LLC
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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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// Testing correctness of the code snippets in the comments of math_opt.h.
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#include <iostream>
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#include <limits>
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#include "absl/status/status.h"
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#include "absl/status/statusor.h"
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#include "ortools/base/init_google.h"
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#include "ortools/base/logging.h"
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#include "ortools/base/status_builder.h"
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#include "ortools/base/status_macros.h"
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#include "ortools/math_opt/cpp/math_opt.h"
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namespace {
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namespace math_opt = ::operations_research::math_opt;
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// Model the problem:
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// max 2.0 * x + y
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// s.t. x + y <= 1.5
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// x in {0.0, 1.0}
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// y in [0.0, 2.5]
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//
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absl::Status Main() {
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math_opt::Model model("my_model");
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const math_opt::Variable x = model.AddBinaryVariable("x");
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const math_opt::Variable y = model.AddContinuousVariable(0.0, 2.5, "y");
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// We can directly use linear combinations of variables ...
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model.AddLinearConstraint(x + y <= 1.5, "c");
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// ... or build them incrementally.
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math_opt::LinearExpression objective_expression;
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objective_expression += 2 * x;
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objective_expression += y;
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model.Maximize(objective_expression);
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ASSIGN_OR_RETURN(const math_opt::SolveResult result,
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Solve(model, math_opt::SolverType::kGscip));
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switch (result.termination.reason) {
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case math_opt::TerminationReason::kOptimal:
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case math_opt::TerminationReason::kFeasible:
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std::cout << "objective value: " << result.objective_value() << std::endl
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<< "value for variable x: " << result.variable_values().at(x)
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<< std::endl;
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return absl::OkStatus();
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default:
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return util::InternalErrorBuilder()
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<< "model failed to solve: " << result.termination;
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}
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}
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} // namespace
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int main(int argc, char** argv) {
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InitGoogle(argv[0], &argc, &argv, true);
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const absl::Status status = Main();
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if (!status.ok()) {
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LOG(QFATAL) << status;
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}
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return 0;
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}
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