Exercise
Consider the following BST:
Exercise How many rotations does it take to balance the above BST?
A) 1
B) 2
C) 3
Solution
Let’s note the heights and balance factors in the original BST:
We can perform a left rotation to bring $4$ to the left of $5$:
We then perform another left rotation to bring $3$ to the left of $5$:
So the answer is B, two rotations.