What Makes a Tree 'Balanced'?

In this chapter, we are going to study what makes a tree balanced. We are also going to look at a high-level description of the algorithm used to determine if a given tree is balanced.


A binary tree is height-balanced if, for each node in the tree, the difference between the height of the right subtree and the left subtree is, at most, one.

Height(LeftSubTree)Height(RightSubTree)<=1|Height(LeftSubTree) - Height(RightSubTree) |<= 1

Look at the illustration below of a height-balanced tree. Notice how the left and right subtrees all appear at the same height.

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