Package the native vc_solver binary and extract it upon use if no local version is present

src/main/java/de/uni/bremen/grapa/library/algorithms/vertexcover/NativeVcSolver.java

@@ -4,10 +4,9 @@ import de.uni.bremen.grapa.library.graphs.api.DirectedEdge;
 import de.uni.bremen.grapa.library.graphs.api.DirectedGraph;
 import de.uni.bremen.grapa.library.graphs.api.Vertex;
 
-import java.io.BufferedInputStream;
-import java.io.IOException;
-import java.io.OutputStreamWriter;
-import java.io.PrintWriter;
+import java.io.*;
+import java.nio.file.Files;
+import java.nio.file.StandardCopyOption;
 import java.util.HashSet;
 import java.util.Scanner;
 import java.util.Set;
@@ -30,7 +29,27 @@ public class NativeVcSolver {
             throw new IllegalArgumentException("Contained a directed edge.");
         }
 
-        final ProcessBuilder processBuilder = new ProcessBuilder("./vc_solver");
+        File solver = new File("vc_solver");
+
+        if (!solver.exists()) {
+            // Use packaged vc_solver instead
+            try (InputStream solverResource = (getClass().getResourceAsStream("/vc_solver"))){
+                solver = File.createTempFile("vc_solver", "");
+                assert solverResource != null;
+                Files.copy(solverResource, solver.toPath(), StandardCopyOption.REPLACE_EXISTING);
+
+                // Set executable flag on solver.
+                // Return value may be unused, cause failure to set this will result in appropriate error later
+                solver.setExecutable(true);
+
+                // Clear the temporary file upon JVM shutdown
+                solver.deleteOnExit();
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        }
+
+        final ProcessBuilder processBuilder = new ProcessBuilder(solver.getAbsolutePath());
 
         try {
             final Process process = processBuilder.start();