Move java examples

examples/java/Circuit.java

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