72 lines
2.5 KiB
C++
72 lines
2.5 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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#include "ortools/math_opt/cpp/objective.h"
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#include "ortools/base/logging.h"
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#include "absl/container/flat_hash_map.h"
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#include "ortools/math_opt/cpp/key_types.h"
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#include "ortools/math_opt/cpp/variable_and_expressions.h"
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#include "ortools/math_opt/indexed_model.h"
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namespace operations_research {
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namespace math_opt {
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void Objective::Maximize(const LinearExpression& objective) const {
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SetObjective(objective, true);
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}
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void Objective::Minimize(const LinearExpression& objective) const {
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SetObjective(objective, false);
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}
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void Objective::SetObjective(const LinearExpression& objective,
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bool is_maximize) const {
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// LinearExpression that have no terms have a null model().
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if (!objective.raw_terms().empty()) {
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CHECK_EQ(objective.model(), model_)
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<< internal::kObjectsFromOtherIndexedModel;
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}
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model_->clear_objective();
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model_->set_is_maximize(is_maximize);
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model_->set_objective_offset(objective.offset());
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for (auto [var, coef] : objective.raw_terms()) {
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model_->set_linear_objective_coefficient(var, coef);
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}
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}
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void Objective::Add(const LinearExpression& objective_terms) const {
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// LinearExpression that have no terms have a null model().
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if (!objective_terms.raw_terms().empty()) {
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CHECK_EQ(objective_terms.model(), model_)
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<< internal::kObjectsFromOtherIndexedModel;
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}
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model_->set_objective_offset(objective_terms.offset() +
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model_->objective_offset());
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for (auto [var, coef] : objective_terms.raw_terms()) {
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model_->set_linear_objective_coefficient(
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var, coef + model_->linear_objective_coefficient(var));
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}
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}
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LinearExpression Objective::AsLinearExpression() const {
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LinearExpression result = model_->objective_offset();
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for (const auto& [v, coef] : model_->linear_objective()) {
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result += Variable(model_, v) * coef;
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}
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return result;
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}
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} // namespace math_opt
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} // namespace operations_research
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