76 lines
3.1 KiB
C++
76 lines
3.1 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_CUMULATIVE_H_
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#define ORTOOLS_SAT_CUMULATIVE_H_
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#include <functional>
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#include <vector>
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#include "absl/types/span.h"
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#include "ortools/sat/integer_base.h"
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#include "ortools/sat/intervals.h"
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#include "ortools/sat/model.h"
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#include "ortools/sat/sat_base.h"
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#include "ortools/sat/scheduling_helpers.h"
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namespace operations_research {
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namespace sat {
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// Adds a cumulative constraint on the given intervals, the associated demands
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// and the capacity expressions.
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//
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// Each interval represents a task to be scheduled in time such that the task
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// consumes the resource during the time range [lb, ub) where lb and ub
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// respectively represent the lower and upper bounds of the corresponding
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// interval variable. The amount of resource consumed by the task is the value
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// of its associated demand variable.
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//
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// The cumulative constraint forces the set of task to be scheduled such that
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// the sum of the demands of all the tasks that overlap any time point cannot
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// exceed the capacity of the resource.
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//
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// This constraint assumes that an interval can be optional or have a size
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// of zero. The demands and the capacity can be any non-negative number.
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//
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// Optimization: If one already have an helper constructed from the interval
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// variable, it can be passed as last argument.
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std::function<void(Model*)> Cumulative(
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const std::vector<Literal>& enforcement_literals,
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const std::vector<IntervalVariable>& vars,
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absl::Span<const AffineExpression> demands, AffineExpression capacity,
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SchedulingConstraintHelper* helper = nullptr);
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// Adds a simple cumulative constraint. See the comment of Cumulative() above
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// for a definition of the constraint. This is only used for testing.
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//
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// This constraint assumes that task demands and the resource capacity are fixed
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// to non-negative number.
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std::function<void(Model*)> CumulativeTimeDecomposition(
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absl::Span<const Literal> enforcement_literals,
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absl::Span<const IntervalVariable> vars,
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absl::Span<const AffineExpression> demands, AffineExpression capacity,
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SchedulingConstraintHelper* helper = nullptr);
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// Another testing code, same assumptions as the CumulativeTimeDecomposition().
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std::function<void(Model*)> CumulativeUsingReservoir(
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absl::Span<const Literal> enforcement_literals,
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absl::Span<const IntervalVariable> vars,
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absl::Span<const AffineExpression> demands, AffineExpression capacity,
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SchedulingConstraintHelper* helper = nullptr);
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} // namespace sat
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} // namespace operations_research
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#endif // ORTOOLS_SAT_CUMULATIVE_H_
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