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
Constraints:
The number of nodes in the tree is in the range [0, 104]. -100 <= Node.val <= 100
Given that a tree node contains a left and right element, I don't see how you can get to the maximum depth of a binary tree without traversing all the paths. So I'm going to traverse them and keep a count of the depth as I traverse it.