Move java examples

examples/java/FlowExample.java

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+// Copyright 2010-2017 Google
+// 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 com.google.ortools.graph.MaxFlow;
+import com.google.ortools.graph.MinCostFlow;
+
+/**
+ * Sample showing how to model using the flow solver.
+ *
+ */
+
+public class FlowExample {
+
+  static {
+    System.loadLibrary("jniortools");
+  }
+
+
+  private static void solveMinCostFlow() {
+    System.out.println("Min Cost Flow Problem - Simple interface");
+    final int numSources = 4;
+    final int numTargets = 4;
+    final int[][] costs = {{90, 75, 75, 80},
+                           {35, 85, 55, 65},
+                           {125, 95, 90, 105},
+                           {45, 110, 95, 115}};
+    final int expectedCost = 275;
+    MinCostFlow minCostFlow = new MinCostFlow();
+    for (int source = 0; source < numSources; ++source) {
+      for (int target = 0; target < numTargets; ++target) {
+        minCostFlow.addArcWithCapacityAndUnitCost(
+            source, numSources + target, 1, costs[source][target]);
+      }
+    }
+    for (int node = 0; node < numSources; ++node) {
+      minCostFlow.setNodeSupply(node, 1);
+      minCostFlow.setNodeSupply(numSources + node, -1);
+    }
+    if (minCostFlow.solve() == MinCostFlow.Status.OPTIMAL) {
+      final long totalFlowCost = minCostFlow.getOptimalCost();
+      System.out.println("total flow = " + totalFlowCost + "/" + expectedCost);
+      for (int i = 0; i < minCostFlow.getNumArcs(); ++i) {
+        if (minCostFlow.getFlow(i) > 0) {
+          System.out.println("From source " + minCostFlow.getTail(i)
+              + " to target " + minCostFlow.getHead(i) + ": cost "
+              + minCostFlow.getUnitCost(i));
+        }
+      }
+    } else {
+      System.out.println("No solution found");
+    }
+  }
+
+  private static void solveMaxFlow() {
+    System.out.println("Max Flow Problem - Simple interface");
+    final int[] tails = {0, 0, 0, 0, 1, 2, 3, 3, 4};
+    final int[] heads = {1, 2, 3, 4, 3, 4, 4, 5, 5};
+    final int[] capacities = {5, 8, 5, 3, 4, 5, 6, 6, 4};
+    final int expectedTotalFlow = 10;
+    MaxFlow maxFlow = new MaxFlow();
+    for (int i = 0; i < tails.length; ++i) {
+      maxFlow.addArcWithCapacity(tails[i], heads[i], capacities[i]);
+    }
+    if (maxFlow.solve(0, 5) == MaxFlow.Status.OPTIMAL) {
+      System.out.println("Total flow " + maxFlow.getOptimalFlow() + "/" + expectedTotalFlow);
+      for (int i = 0; i < maxFlow.getNumArcs(); ++i) {
+        System.out.println("From source " + maxFlow.getTail(i)
+            + " to target " + maxFlow.getHead(i) + ": "
+            + maxFlow.getFlow(i) + " / " + maxFlow.getCapacity(i));
+      }
+      // TODO(user): Our SWIG configuration does not currently handle these
+      // functions correctly in Java:
+      // maxFlow.getSourceSideMinCut(...);
+      // maxFlow.getSinkSideMinCut(...);
+    } else {
+      System.out.println("There was an issue with the input.");
+    }
+  }
+
+  public static void main(String[] args) throws Exception {
+    FlowExample.solveMinCostFlow();
+    FlowExample.solveMaxFlow();
+  }
+}