104. Maximum Depth of Binary Tree.js

// Given the root of a binary tree, return its maximum depth.

// A binary tree's maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.

// Example 1:

// Input: root = [3,9,20,null,null,15,7]
// Output: 3
// Example 2:

// Input: root = [1,null,2]
// Output: 2

const maxDepth = root => {
	if (!root) return 0

	let leftDepth = maxDepth(root.left)
	let rightDepth = maxDepth(root.right)

	return Math.max(leftDepth, rightDepth) + 1
}