Memory limiter queue control when deleting empty solutions.

zpp-solver/mcts-solver/src/main/java/eu/melodic/upperware/mcts_solver/solver/mcts/tree/MemoryLimiter.java

@@ -11,4 +11,6 @@ public interface MemoryLimiter {
     void decreaseCount(int count);
     // Creates node with certain value.
     Node createNode(int value);
+    // Removes node from queue, does nothing if it's not in queue.
+    void removeNodeFromQueue(Node node);
 }
\ No newline at end of file

zpp-solver/mcts-solver/src/main/java/eu/melodic/upperware/mcts_solver/solver/mcts/tree/Tree.java

@@ -89,6 +89,7 @@ public abstract class Tree {
         node.getParent().removeChild(node);
 
         if (node.getParent() != root && node.getParent().getChildrenSize() == 0) {
+            memoryLimiter.removeNodeFromQueue(node.getParent());
             removeLeaf(node.getParent());
         }
         // There's a corner case in which root can lose its all children.

zpp-solver/mcts-solver/src/main/java/eu/melodic/upperware/mcts_solver/solver/mcts/tree_impl/MemoryLimiterImpl.java

@@ -12,14 +12,17 @@ public class MemoryLimiterImpl implements MemoryLimiter {
         this.limit = limit;
     }
 
+    @Override
     public boolean shouldPruneTree() {
         return count > limit && !accessQueue.empty();
     }
 
+    @Override
     public Node popNodeToPrune() {
         return accessQueue.popFront();
     }
 
+    @Override
     public void updateRecentlyAccessedNodes(Node startingNode) {
         Node current = startingNode;
 
@@ -31,15 +34,22 @@ public class MemoryLimiterImpl implements MemoryLimiter {
         }
     }
 
+    @Override
     public void decreaseCount(int count) {
         this.count -= count;
     }
 
+    @Override
     public Node createNode(int value) {
         count++;
         return new NodeImpl(value);
     }
 
+    @Override
+    public void removeNodeFromQueue(Node node) {
+        accessQueue.removeNodeFromQueue((NodeImpl) node);
+    }
+
     private void updateRecentlyAccessedNode(Node node) {
         accessQueue.pushBack(node);
     }

zpp-solver/mcts-solver/src/main/java/eu/melodic/upperware/mcts_solver/solver/mcts/tree_impl/Queue.java

@@ -42,7 +42,7 @@ public class Queue {
         return front == null;
     }
 
-    private void removeNodeFromQueue(NodeImpl node) {
+    public void removeNodeFromQueue(NodeImpl node) {
         NodeImpl previous = node.getQueueLinker().getPrevious();
         NodeImpl next = node.getQueueLinker().getNext();