When the left sub-tree of the tree is one level higher than that of the right sub-tree, then the balance factor is __________.

The correct answer is 1.

Key Points

• The balance factor in an AVL tree is calculated as the height of the left sub-tree minus the height of the right sub-tree.
• When the left sub-tree of the tree is one level higher than that of the right sub-tree, the balance factor is 1.
• A balance factor of 1 indicates that the tree is still balanced and does not require any rotations.
• The balance factor is used to ensure that the tree remains balanced after insertions and deletions.

Additional Information

• The balance factor can be -1, 0, or 1 in an AVL tree to maintain its balance.
• If the balance factor becomes greater than 1 or less than -1, rotations are performed to balance the tree.
• AVL trees provide faster lookups compared to unbalanced binary search trees.
• Named after its inventors, Adelson-Velsky and Landis, AVL trees were the first self-balancing binary search trees.