sec balanced trees (as (bfigure double rotation in an avl tree this operation occurs when the excess node (in subtree bis in the right child of the left child of the unbalanced node labeled by rearranging the nodes as shownwe preserve the bst propertyas well as re-balance the tree to preserve the avl tree balance property the case where the excess node is in the left child of the right child of is handled in the same way found to be unbalanced deletion is similarhowever consideration for unbalanced nodes must begin at the level of the deletemin operation example in figure ( )the bottom-most unbalanced node has value the excess node (with value is in the right subtree of the left child of so we have an example of case this requires double rotation to fix after the rotation becomes the left child of becomes the left child of and becomes the right child of the splay tree like the avl treethe splay tree is not actually data structure per se but rather is collection of rules for improving the performance of bst these rules govern modifications made to the bst whenever searchinsertor delete operation is performed their purpose is to provide guarantees on the time required by series of operationsthereby avoiding the worst-case linear time behavior of standard bst operations no single operation in the splay tree is guaranteed to be efficient insteadthe splay tree access rules guarantee that series of operations will take