Data Structures | Balanced Binary Search Trees | Question 4

Which of the following is AVL Tree?

A
        100
     /      \
    50       200
   /           \
 10            300


B
           100
       /       \
     50        200
    /        /     \
  10       150     300
 /
5


C
            100
       /          \
     50            200
    /  \          /     \
  10    60       150     300
 /                 \        \
5                   180       400

(A) Only A
(B) A and C
(C) A, B and C
(D) Only B

Answer: (B)
Explanation: A Binary Search Tree is AVL if balance factor of every node is either -1 or 0 or 1. Balance factor of a node X is [(height of X->left) – (height of X->right)].

In Tree B, the node with value 50 has balance factor 2. That is why B is not an AVL tree.
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