Easy · Trees

Is balanced

Given the root of a binary tree, return true if it is height-balanced (at every node, the heights of the left and right subtrees differ by at most 1) and false otherwise. An empty tree is balanced.

Examples

Example 1

{
  "tree": [3, 9, 20, null, null, 15, 7]
}

Output: balanced

Example 2

{
  "tree": [1, 2, null, 3]
}

Output: not balanced

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