121 lines
4.5 KiB
C++
121 lines
4.5 KiB
C++
// Copyright 2010-2025 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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#ifndef ORTOOLS_SAT_2D_TRY_EDGE_PROPAGATOR_H_
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#define ORTOOLS_SAT_2D_TRY_EDGE_PROPAGATOR_H_
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#include <cstdint>
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#include <optional>
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#include <utility>
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#include <vector>
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#include "ortools/sat/diffn_util.h"
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#include "ortools/sat/integer.h"
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#include "ortools/sat/integer_base.h"
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#include "ortools/sat/model.h"
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#include "ortools/sat/no_overlap_2d_helper.h"
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#include "ortools/sat/synchronization.h"
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#include "ortools/sat/util.h"
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#include "ortools/util/bitset.h"
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namespace operations_research {
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namespace sat {
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// Propagator that for each boxes participating in a no_overlap_2d constraint
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// try to find the leftmost valid position that is compatible with all the
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// other boxes. If none is found, it will propagate a conflict. Otherwise, if
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// it is different from the current x_min, it will propagate the new x_min.
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void CreateAndRegisterTryEdgePropagator(NoOverlap2DConstraintHelper* helper,
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Model* model,
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GenericLiteralWatcher* watcher,
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int priority);
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// Exposed for testing.
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class TryEdgeRectanglePropagator : public PropagatorInterface {
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public:
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TryEdgeRectanglePropagator(bool x_is_forward_after_swap,
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bool y_is_forward_after_swap, bool swap_x_and_y,
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NoOverlap2DConstraintHelper* helper, Model* model)
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: helper_(*helper),
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shared_stats_(model->GetOrCreate<SharedStatistics>()),
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x_is_forward_after_swap_(x_is_forward_after_swap),
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y_is_forward_after_swap_(y_is_forward_after_swap),
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swap_x_and_y_(swap_x_and_y) {}
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~TryEdgeRectanglePropagator() override;
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bool Propagate() final;
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int RegisterWith(GenericLiteralWatcher* watcher);
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protected:
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// placed_boxes_ is a list that is only meaningful for indices for which
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// is_in_cache_[box_index] is true. After applying this condition,
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// placed_boxes_ contains a list of boxes placed at their current x_min and
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// that does not overlap with the mandatory region of any other box in
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// placed_boxes_. In other words, there is no point on looking for any
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// propagation for this heuristic between boxes that are already in
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// placed_boxes_.
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std::vector<Rectangle> placed_boxes_;
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std::vector<bool> is_in_cache_;
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std::vector<Rectangle> mandatory_regions_;
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std::vector<RectangleInRange> active_box_ranges_;
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std::vector<bool> is_active_;
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Bitset64<int> has_mandatory_region_;
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std::vector<int> changed_item_;
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std::vector<int> changed_mandatory_;
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virtual bool ExplainAndPropagate(
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const std::vector<std::pair<int, std::optional<IntegerValue>>>&
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found_propagations);
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// This function assumes that a propagation is found and the box with index
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// `box_index` cannot be placed to the left of new_x_min. It returns a list of
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// indices of boxes that defines a subproblem where the propagation is still
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// valid, including `box_index` itself.
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std::vector<int> GetMinimumProblemWithPropagation(int box_index,
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IntegerValue new_x_min);
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private:
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void PopulateActiveBoxRanges();
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NoOverlap2DConstraintHelper& helper_;
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SharedStatistics* shared_stats_;
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bool x_is_forward_after_swap_;
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bool y_is_forward_after_swap_;
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bool swap_x_and_y_;
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std::vector<IntegerValue> cached_y_hint_;
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std::vector<IntegerValue> potential_x_positions_;
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std::vector<IntegerValue> potential_y_positions_;
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int64_t num_conflicts_ = 0;
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int64_t num_propagations_ = 0;
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int64_t num_calls_ = 0;
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CompactVectorVector<int> conflicts_per_x_and_y_;
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bool CanPlace(int box_index,
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const std::pair<IntegerValue, IntegerValue>& position,
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CompactVectorVector<int>* with_conflicts = nullptr) const;
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TryEdgeRectanglePropagator(const TryEdgeRectanglePropagator&) = delete;
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TryEdgeRectanglePropagator& operator=(const TryEdgeRectanglePropagator&) =
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delete;
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};
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} // namespace sat
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} // namespace operations_research
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#endif // ORTOOLS_SAT_2D_TRY_EDGE_PROPAGATOR_H_
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