97 lines
3.3 KiB
C#
97 lines
3.3 KiB
C#
// Copyright 2010-2022 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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using System;
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using Google.OrTools.Sat;
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using Google.OrTools.Util;
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public class VarArraySolutionPrinter : CpSolverSolutionCallback
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{
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public VarArraySolutionPrinter(IntVar[] variables)
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{
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variables_ = variables;
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}
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public override void OnSolutionCallback()
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{
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{
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foreach (IntVar v in variables_)
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{
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Console.Write(String.Format("{0}={1} ", v.ToString(), Value(v)));
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}
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Console.WriteLine();
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}
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}
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private IntVar[] variables_;
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}
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public class StepFunctionSampleSat
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{
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static void Main()
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{
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// Create the CP-SAT model.
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CpModel model = new CpModel();
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// Declare our primary variable.
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IntVar x = model.NewIntVar(0, 20, "x");
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// Create the expression variable and implement the step function
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// Note it is not defined for var == 2.
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//
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// - 3
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// -- -- --------- 2
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// 1
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// -- --- 0
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// 0 ================ 20
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//
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IntVar expr = model.NewIntVar(0, 3, "expr");
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// expr == 0 on [5, 6] U [8, 10]
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ILiteral b0 = model.NewBoolVar("b0");
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model.AddLinearExpressionInDomain(x, Domain.FromValues(new long[] { 5, 6, 8, 9, 10 })).OnlyEnforceIf(b0);
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model.Add(expr == 0).OnlyEnforceIf(b0);
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// expr == 2 on [0, 1] U [3, 4] U [11, 20]
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ILiteral b2 = model.NewBoolVar("b2");
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model
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.AddLinearExpressionInDomain(
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x,
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Domain.FromIntervals(new long[][] { new long[] { 0, 1 }, new long[] { 3, 4 }, new long[] { 11, 20 } }))
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.OnlyEnforceIf(b2);
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model.Add(expr == 2).OnlyEnforceIf(b2);
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// expr == 3 when x == 7
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ILiteral b3 = model.NewBoolVar("b3");
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model.Add(x == 7).OnlyEnforceIf(b3);
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model.Add(expr == 3).OnlyEnforceIf(b3);
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// At least one bi is true. (we could use a sum == 1).
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model.AddBoolOr(new ILiteral[] { b0, b2, b3 });
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// Search for x values in increasing order.
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model.AddDecisionStrategy(new IntVar[] { x }, DecisionStrategyProto.Types.VariableSelectionStrategy.ChooseFirst,
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DecisionStrategyProto.Types.DomainReductionStrategy.SelectMinValue);
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// Create the solver.
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CpSolver solver = new CpSolver();
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// Force solver to follow the decision strategy exactly.
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// Tells the solver to enumerate all solutions.
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solver.StringParameters = "search_branching:FIXED_SEARCH, enumerate_all_solutions:true";
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VarArraySolutionPrinter cb = new VarArraySolutionPrinter(new IntVar[] { x, expr });
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solver.Solve(model, cb);
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}
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}
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