Allow loading different problems

src/main/java/de/uni/bremen/grapa/library/io/implementation/BasicUndirectedGraphImporterExporter.java

@@ -32,6 +32,21 @@ public class BasicUndirectedGraphImporterExporter
         implements Exporter<BasicUndirectedGraph>,
         Importer<BasicUndirectedGraph> {
 
+    private String problem;
+
+    public BasicUndirectedGraphImporterExporter() {
+        this("cep");
+    }
+
+    /**
+     * Specifies which problem to look for.
+     *
+     * @param problem name of the problem
+     */
+    public BasicUndirectedGraphImporterExporter(String problem) {
+        this.problem = problem;
+    }
+
     @Override
     public void exportToFile(final BasicUndirectedGraph graph, final String path) throws IOException {
         export(graph, new FileWriter(path));
@@ -89,7 +104,7 @@ public class BasicUndirectedGraphImporterExporter
             if (nextLine.startsWith("p")) { //Pace Problem importtype
                 //block needed for pace
                 String[] arguments = nextLine.split(" ");
-                if (!(arguments[1].equals("cep") || arguments[1].equals("td"))) {
+                if (!(arguments[1].equals(problem) || arguments[1].equals("td"))) {
                     System.err.println("Wrong problem see pace 2021 documentation");
                     break;
                 }