121 lines
3.1 KiB
Java
121 lines
3.1 KiB
Java
// Copyright 2011 Hakan Kjellerstrand hakank@gmail.com
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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 java.io.*;
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import java.util.*;
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import java.text.*;
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import com.google.ortools.constraintsolver.DecisionBuilder;
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import com.google.ortools.constraintsolver.IntVar;
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import com.google.ortools.constraintsolver.Solver;
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public class Circuit {
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static {
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System.loadLibrary("jniortools");
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}
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/**
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* circuit(solver, x)
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*
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* A decomposition of the global constraint circuit, based
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* on some observation of the orbits in an array.
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*
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* Note: The domain of x must be 0..n-1 (not 1..n)
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* since Java is 0-based.
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*/
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public static void circuit(Solver solver, IntVar[] x) {
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int n = x.length;
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IntVar[] z = solver.makeIntVarArray(n, 0, n - 1, "z");
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solver.addConstraint(solver.makeAllDifferent(x));
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solver.addConstraint(solver.makeAllDifferent(z));
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// put the orbit of x[0] in z[0..n-1]
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solver.addConstraint(solver.makeEquality(z[0], x[0]));
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for(int i = 1; i < n-1; i++) {
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solver.addConstraint(
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solver.makeEquality(z[i],
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solver.makeElement(x, z[i-1]).var()));
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}
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// z may not be 0 for i < n-1
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for(int i = 1; i < n - 1; i++) {
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solver.addConstraint(solver.makeNonEquality(z[i], 0));
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}
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// when i = n-1 it must be 0
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solver.addConstraint(solver.makeEquality(z[n - 1], 0));
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}
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/**
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*
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* Implements a (decomposition) of the global constraint circuit.
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* See http://www.hakank.org/google_or_tools/circuit.py
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*
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*/
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private static void solve(int n) {
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Solver solver = new Solver("Circuit");
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//
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// variables
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//
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IntVar[] x = solver.makeIntVarArray(n, 0, n - 1, "x");
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//
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// constraints
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//
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circuit(solver, x);
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//
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// search
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//
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DecisionBuilder db = solver.makePhase(x,
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solver.INT_VAR_DEFAULT,
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solver.INT_VALUE_DEFAULT);
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solver.newSearch(db);
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//
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// output
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//
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while (solver.nextSolution()) {
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for(int i = 0; i < n; i++) {
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System.out.print(x[i].value() + " ");
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}
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System.out.println();
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}
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solver.endSearch();
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// Statistics
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System.out.println();
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System.out.println("Solutions: " + solver.solutions());
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System.out.println("Failures: " + solver.failures());
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System.out.println("Branches: " + solver.branches());
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System.out.println("Wall time: " + solver.wallTime() + "ms");
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}
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public static void main(String[] args) throws Exception {
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int n = 5;
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if (args.length > 0) {
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n = Integer.parseInt(args[0]);
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}
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Circuit.solve(n);
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}
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}
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