Fix issue where cost is missing

Author: IoannisPanagiotas

algo/src/main/java/org/neo4j/gds/pricesteiner/EdgeEventsQueue.java

@@ -76,7 +76,7 @@ void addBothWays(long s, long t, long edgePart1, long edgePart2, double w){
      void addWithCheck(long s,  long edgePart, double w){
          var pairingHeapOfs  = pairingHeaps.get(s);
          pairingHeapOfs.add(edgePart,w);
-         if (w < edgeEventsPriorityQueue.cost(s)){
+         if (!edgeEventsPriorityQueue.containsElement(s) || w  < edgeEventsPriorityQueue.cost(s)){
                edgeEventsPriorityQueue.set(s, w);
          }
      }

algo/src/test/java/org/neo4j/gds/pricesteiner/EdgeEventsQueueTest.java

@@ -121,6 +121,22 @@ void mergeShouldNotKeepOldCopiesAround(){
         assertThat(edgeEventsQueue.top()).isEqualTo(11L);
         assertThat(edgeEventsQueue.nextEventTime()).isEqualTo(20);
 
+    }
+
+    @Test
+    void shouldReAddCorrectly(){
+
+        var edgeEventsQueue = new EdgeEventsQueue(2);
+        edgeEventsQueue.addBothWays(0,1,0,1,10);
+        edgeEventsQueue.performInitialAssignment(2);
+        edgeEventsQueue.deactivateCluster(1);
+        assertThat(edgeEventsQueue.top()).isEqualTo(0);
+        edgeEventsQueue.pop();
+        assertThat(edgeEventsQueue.nextEventTime()).isEqualTo(Double.MAX_VALUE);
+        edgeEventsQueue.addWithCheck(0,0,10);
+        assertThat(edgeEventsQueue.top()).isEqualTo(0);
+        assertThat(edgeEventsQueue.nextEventTime()).isEqualTo(10);
+
 
     }