82 lines
2.7 KiB
Go
82 lines
2.7 KiB
Go
// Copyright 2010-2024 Google LLC
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
// The channeling_sample_sat command is a simple example of a channeling constraint.
|
|
package main
|
|
|
|
import (
|
|
"fmt"
|
|
|
|
"github.com/golang/glog"
|
|
"golang/protobuf/v2/proto/proto"
|
|
cmpb "ortools/sat/cp_model_go_proto"
|
|
"ortools/sat/go/cpmodel"
|
|
sppb "ortools/sat/sat_parameters_go_proto"
|
|
)
|
|
|
|
func channelingSampleSat() error {
|
|
// Create the CP-SAT model.
|
|
model := cpmodel.NewCpModelBuilder()
|
|
|
|
// Declare our two primary variables.
|
|
x := model.NewIntVar(0, 10)
|
|
y := model.NewIntVar(0, 10)
|
|
|
|
// Declare our intermediate Boolean variable.
|
|
b := model.NewBoolVar()
|
|
|
|
// Implement b == (x > 5).
|
|
model.AddGreaterOrEqual(x, cpmodel.NewConstant(5)).OnlyEnforceIf(b)
|
|
model.AddLessThan(x, model.NewConstant(5)).OnlyEnforceIf(b.Not())
|
|
|
|
// Create our two half-reified constraints.
|
|
// First, b implies (y == 10 - x).
|
|
model.AddEquality(cpmodel.NewLinearExpr().Add(x).Add(y), cpmodel.NewConstant(10)).OnlyEnforceIf(b)
|
|
// Second, b.Not() implies (y == 0).
|
|
model.AddEquality(y, cpmodel.NewConstant(0)).OnlyEnforceIf(b.Not())
|
|
|
|
// Search for x values in increasing order.
|
|
model.AddDecisionStrategy([]cpmodel.IntVar{x}, cmpb.DecisionStrategyProto_CHOOSE_FIRST, cmpb.DecisionStrategyProto_SELECT_MIN_VALUE)
|
|
|
|
// Create a solver and solve with a fixed search.
|
|
m, err := model.Model()
|
|
if err != nil {
|
|
return fmt.Errorf("failed to instantiate the CP model: %w", err)
|
|
}
|
|
params := sppb.SatParameters_builder{
|
|
FillAdditionalSolutionsInResponse: proto.Bool(true),
|
|
EnumerateAllSolutions: proto.Bool(true),
|
|
SolutionPoolSize: proto.Int32(11),
|
|
SearchBranching: sppb.SatParameters_FIXED_SEARCH.Enum(),
|
|
}.Build()
|
|
response, err := cpmodel.SolveCpModelWithParameters(m, params)
|
|
if err != nil {
|
|
return fmt.Errorf("failed to solve the model: %w", err)
|
|
}
|
|
|
|
fmt.Printf("Status: %v\n", response.GetStatus())
|
|
|
|
for _, additionalSolution := range response.GetAdditionalSolutions() {
|
|
vs := additionalSolution.GetValues()
|
|
fmt.Printf("x: %v y: %v b: %v\n", vs[x.Index()], vs[y.Index()], vs[b.Index()])
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func main() {
|
|
if err := channelingSampleSat(); err != nil {
|
|
glog.Exitf("channelingSampleSat returned with error: %v", err)
|
|
}
|
|
}
|