fixed processing sequence to avoid non-deterministic behavior

if there is more than one route option with the same travel time albeit
different length, the route found depends on the sequence of link
processing. That is, route choice depends on the implementation of the
Network/NetworkReader and/or the sequence of links in the network file.

matsim/src/main/java/org/matsim/core/router/speedy/SpeedyGraph.java

@@ -5,7 +5,10 @@
 import org.matsim.api.core.v01.network.Network;
 import org.matsim.api.core.v01.network.Node;
 
+import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
 
 /**
  * Implements a highly optimized data structure for representing a MATSim network. Optimized to use as little memory as possible, and thus to fit as much memory as possible into CPU caches for high
@@ -70,7 +73,11 @@ public SpeedyGraph(Network network) {
         for (Node node : network.getNodes().values()) {
             this.nodes[node.getId().index()] = node;
         }
-        for (Link link : network.getLinks().values()) {
+
+        List<Id<Link>> linkIds = new ArrayList<>(network.getLinks().keySet());
+        Collections.sort(linkIds);
+        for (Id<Link> linkId : linkIds) {
+        	Link link = network.getLinks().get(linkId);
             addLink(link);
         }
     }