fix bug in casting for bsts

Author: justcoding121

src/Advanced.Algorithms/DataStructures/Tree/AvlTree.cs

@@ -419,7 +419,7 @@ private AVLTreeNode<T> find(T value)
                 return nodeLookUp[value] as AVLTreeNode<T>;
             }
 
-            return Root.Find<T>(value) as AVLTreeNode<T>;
+            return Root.Find(value).Item1 as AVLTreeNode<T>;
         }
 
         //find the node with the given identifier among descendants of parent and parent

src/Advanced.Algorithms/DataStructures/Tree/BST.cs

@@ -395,7 +395,7 @@ private BSTNode<T> find(BSTNode<T> parent, T value)
         //O(log(n)) worst O(n) for unbalanced tree
         private BSTNodeBase<T> find(T value)
         {
-            return Root.Find<T>(value) as BSTNodeBase<T>;
+            return Root.Find<T>(value).Item1 as BSTNodeBase<T>;
         }
 
         /// <summary>

src/Advanced.Algorithms/DataStructures/Tree/SplayTree.cs

@@ -494,7 +494,7 @@ private SplayTreeNode<T> leftRotate(SplayTreeNode<T> currentRoot)
         //O(log(n)) worst O(n) for unbalanced tree
         private BSTNodeBase<T> find(T value)
         {
-            return Root.Find<T>(value) as BSTNodeBase<T>;
+            return Root.Find<T>(value).Item1 as BSTNodeBase<T>;
         }
 
         /// <summary>

src/Advanced.Algorithms/DataStructures/Tree/TreapTree.cs

@@ -489,7 +489,7 @@ private TreapTreeNode<T> leftRotate(TreapTreeNode<T> currentRoot)
         //O(log(n)) worst O(n) for unbalanced tree
         private BSTNodeBase<T> find(T value)
         {
-            return Root.Find<T>(value) as BSTNodeBase<T>;
+            return Root.Find<T>(value).Item1 as BSTNodeBase<T>;
         }
 
         /// <summary>