4f381f6d07
* bump abseil to 20250814 * bump protobuf to v32.0 * cmake: add ccache auto support * backport flatzinc, math_opt and sat update
86 lines
2.8 KiB
Go
86 lines
2.8 KiB
Go
// 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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// [START program]
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// The channeling_sample_sat command is a simple example of a channeling constraint.
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package main
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import (
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"fmt"
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log "github.com/golang/glog"
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"github.com/google/or-tools/ortools/sat/go/cpmodel"
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"google.golang.org/protobuf/proto"
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cmpb "github.com/google/or-tools/ortools/sat/proto/cpmodel"
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sppb "github.com/google/or-tools/ortools/sat/proto/satparameters"
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)
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func channelingSampleSat() error {
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// Create the CP-SAT model.
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model := cpmodel.NewCpModelBuilder()
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// Declare our two primary variables.
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x := model.NewIntVar(0, 10)
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y := model.NewIntVar(0, 10)
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// Declare our intermediate Boolean variable.
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b := model.NewBoolVar()
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// Implement b == (x > 5).
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model.AddGreaterOrEqual(x, cpmodel.NewConstant(5)).OnlyEnforceIf(b)
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model.AddLessThan(x, model.NewConstant(5)).OnlyEnforceIf(b.Not())
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// Create our two half-reified constraints.
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// First, b implies (y == 10 - x).
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model.AddEquality(cpmodel.NewLinearExpr().Add(x).Add(y), cpmodel.NewConstant(10)).OnlyEnforceIf(b)
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// Second, b.Not() implies (y == 0).
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model.AddEquality(y, cpmodel.NewConstant(0)).OnlyEnforceIf(b.Not())
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// Search for x values in increasing order.
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model.AddDecisionStrategy([]cpmodel.IntVar{x}, cmpb.DecisionStrategyProto_CHOOSE_FIRST, cmpb.DecisionStrategyProto_SELECT_MIN_VALUE)
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// Create a solver and solve with a fixed search.
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m, err := model.Model()
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if err != nil {
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return fmt.Errorf("failed to instantiate the CP model: %w", err)
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}
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params := &sppb.SatParameters{
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FillAdditionalSolutionsInResponse: proto.Bool(true),
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EnumerateAllSolutions: proto.Bool(true),
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SolutionPoolSize: proto.Int32(11),
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SearchBranching: sppb.SatParameters_FIXED_SEARCH.Enum(),
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}
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response, err := cpmodel.SolveCpModelWithParameters(m, params)
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if err != nil {
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return fmt.Errorf("failed to solve the model: %w", err)
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}
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fmt.Printf("Status: %v\n", response.GetStatus())
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for _, additionalSolution := range response.GetAdditionalSolutions() {
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vs := additionalSolution.GetValues()
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fmt.Printf("x: %v y: %v b: %v\n", vs[x.Index()], vs[y.Index()], vs[b.Index()])
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}
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return nil
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}
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func main() {
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if err := channelingSampleSat(); err != nil {
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log.Exitf("channelingSampleSat returned with error: %v", err)
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}
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}
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// [END program]
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