Move java examples

examples/java/SetCoveringDeployment.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;
+import com.google.ortools.constraintsolver.OptimizeVar;
+
+public class SetCoveringDeployment {
+
+  static {
+    System.loadLibrary("jniortools");
+  }
+
+
+  /**
+   *
+   * Solves a set covering deployment problem.
+   * See http://www.hakank.org/google_or_tools/set_covering_deployment.py
+   *
+   */
+  private static void solve() {
+
+    Solver solver = new Solver("SetCoveringDeployment");
+
+    //
+    // data
+    //
+
+    // From http://mathworld.wolfram.com/SetCoveringDeployment.html
+    String[] countries = {"Alexandria",
+                           "Asia Minor",
+                           "Britain",
+                           "Byzantium",
+                           "Gaul",
+                           "Iberia",
+                           "Rome",
+                           "Tunis"};
+
+    int n = countries.length;
+
+    // the incidence matrix (neighbours)
+    int[][] mat = {{0, 1, 0, 1, 0, 0, 1, 1},
+                   {1, 0, 0, 1, 0, 0, 0, 0},
+                   {0, 0, 0, 0, 1, 1, 0, 0},
+                   {1, 1, 0, 0, 0, 0, 1, 0},
+                   {0, 0, 1, 0, 0, 1, 1, 0},
+                   {0, 0, 1, 0, 1, 0, 1, 1},
+                   {1, 0, 0, 1, 1, 1, 0, 1},
+                   {1, 0, 0, 0, 0, 1, 1, 0}};
+
+
+    //
+    // variables
+    //
+
+    // First army
+    IntVar[] x = solver.makeIntVarArray(n, 0, 1, "x");
+
+    // Second (reserve) army
+    IntVar[] y = solver.makeIntVarArray(n, 0, 1, "y");
+
+    // total number of armies
+    IntVar num_armies = solver.makeSum(solver.makeSum(x),
+                                       solver.makeSum(y)).var();
+
+    //
+    // constraints
+    //
+
+    //
+    //  Constraint 1: There is always an army in a city
+    //                (+ maybe a backup)
+    //                Or rather: Is there a backup, there
+    //                must be an an army
+    //
+    for(int i = 0; i < n; i++) {
+      solver.addConstraint(solver.makeGreaterOrEqual(x[i], y[i]));
+    }
+
+    //
+    // Constraint 2: There should always be an backup
+    //               army near every city
+    //
+    for(int i = 0; i < n; i++) {
+      ArrayList<IntVar> count_neighbours = new ArrayList<IntVar>();
+      for(int j = 0; j < n; j++) {
+        if (mat[i][j] == 1) {
+          count_neighbours.add(y[j]);
+        }
+      }
+      solver.addConstraint(
+          solver.makeGreaterOrEqual(
+              solver.makeSum(x[i],
+                  solver.makeSum(
+                      count_neighbours.toArray(new IntVar[1])).var()), 1));
+    }
+
+    //
+    // objective
+    //
+    OptimizeVar objective = solver.makeMinimize(num_armies, 1);
+
+
+    //
+    // search
+    //
+    DecisionBuilder db = solver.makePhase(x,
+                                          solver.INT_VAR_DEFAULT,
+                                          solver.INT_VALUE_DEFAULT);
+    solver.newSearch(db, objective);
+
+    //
+    // output
+    //
+    while (solver.nextSolution()) {
+      System.out.println("num_armies: " + num_armies.value());
+      for(int i = 0; i < n; i++) {
+        if (x[i].value() == 1) {
+          System.out.print("Army: " + countries[i] + " ");
+        }
+        if (y[i].value() == 1) {
+          System.out.println("Reserve army: " + countries[i]);
+        }
+      }
+
+    }
+    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 {
+
+    SetCoveringDeployment.solve();
+
+  }
+}