# Leetcode 110 - Balanced binary tree

`Note`

- Need a helper
`height`

AKA`maxHeight`

- Recursively to check if a node’s
`left subtree's height`

and`right subtree's height`

differ by no more than`1`

.

Given a binary tree, determine if it is height-balanced.

For this problem, a height-balanced binary tree is defined as:

a binary tree in which the left and right subtrees of every node differ in height by no more than 1.

**Example**

1 | Input: root = [3,9,20,null,null,15,7] |

1 | /** |