Move java examples

examples/java/SetCovering.java

@@ -0,0 +1,118 @@
+// 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 SetCovering {
+
+  static {
+    System.loadLibrary("jniortools");
+  }
+
+
+  /**
+   *
+   * Solves a set covering problem.
+   * See http://www.hakank.org/google_or_tools/set_covering.py
+   *
+   */
+  private static void solve() {
+
+    Solver solver = new Solver("SetCovering");
+
+    //
+    // data
+    //
+    // Placing of firestations, from Winston 'Operations Research',
+    // page 486.
+    int min_distance = 15;
+    int num_cities = 6;
+
+    int[][] distance = {{ 0,10,20,30,30,20},
+                        {10, 0,25,35,20,10},
+                        {20,25, 0,15,30,20},
+                        {30,35,15, 0,15,25},
+                        {30,20,30,15, 0,14},
+                        {20,10,20,25,14, 0}};
+
+
+    //
+    // variables
+    //
+    IntVar[] x = solver.makeIntVarArray(num_cities, 0, 1, "x");
+    IntVar z = solver.makeSum(x).var();
+
+
+    //
+    // constraints
+    //
+
+    // ensure that all cities are covered
+    for(int i = 0; i < num_cities; i++) {
+      ArrayList<IntVar> b = new ArrayList<IntVar>();
+      for(int j = 0; j < num_cities; j++) {
+        if (distance[i][j] <= min_distance) {
+          b.add(x[j]);
+        }
+      }
+      solver.addConstraint(
+          solver.makeSumGreaterOrEqual(b.toArray(new IntVar[1]), 1));
+
+    }
+
+    //
+    // objective
+    //
+    OptimizeVar objective = solver.makeMinimize(z, 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("z: " + z.value());
+      System.out.print("x: ");
+      for(int i = 0; i < num_cities; 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 {
+    SetCovering.solve();
+  }
+}