97 lines
3.4 KiB
Java
97 lines
3.4 KiB
Java
// Copyright 2010-2018 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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import com.google.ortools.sat.CpModel;
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import com.google.ortools.sat.CpSolver;
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import com.google.ortools.sat.CpSolverSolutionCallback;
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import com.google.ortools.sat.DecisionStrategyProto;
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import com.google.ortools.sat.Domain;
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import com.google.ortools.sat.IntVar;
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import com.google.ortools.sat.Literal;
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import com.google.ortools.sat.SatParameters;
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/** Link integer constraints together. */
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public class StepFunctionSampleSat {
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static {
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System.loadLibrary("jniortools");
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}
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public static void main(String[] args) throws Exception {
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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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Literal b0 = model.newBoolVar("b0");
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model.addSumInDomain(new IntVar[] {x},
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Domain.fromValues(new long[] {5, 6, 8, 9, 10})).onlyEnforceIf(b0);
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model.addEquality(expr, 0).onlyEnforceIf(b0);
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// expr == 2 on [0, 1] U [3, 4] U [11, 20]
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Literal b2 = model.newBoolVar("b2");
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model.addSumInDomain(new IntVar[] {x},
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Domain.fromIntervals(new long[] {0, 1, 3, 4, 11, 20})).onlyEnforceIf(b2);
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model.addEquality(expr, 2).onlyEnforceIf(b2);
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// expr == 3 when x = 7
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Literal b3 = model.newBoolVar("b3");
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model.addEquality(x, 7).onlyEnforceIf(b3);
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model.addEquality(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 Literal[] {b0, b2, b3});
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// Search for x values in increasing order.
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model.addDecisionStrategy(new IntVar[] {x},
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DecisionStrategyProto.VariableSelectionStrategy.CHOOSE_FIRST,
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DecisionStrategyProto.DomainReductionStrategy.SELECT_MIN_VALUE);
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// Create the solver.
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CpSolver solver = new CpSolver();
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// Force the solver to follow the decision strategy exactly.
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solver.getParameters().setSearchBranching(SatParameters.SearchBranching.FIXED_SEARCH);
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// Solve the problem with the printer callback.
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solver.searchAllSolutions(model, new CpSolverSolutionCallback() {
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public CpSolverSolutionCallback init(IntVar[] variables) {
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variableArray = variables;
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return this;
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}
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@Override
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public void onSolutionCallback() {
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for (IntVar v : variableArray) {
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System.out.printf("%s=%d ", v.getName(), value(v));
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}
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System.out.println();
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}
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private IntVar[] variableArray;
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}.init(new IntVar[] {x, expr}));
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}
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}
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