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




 # Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def maxDepth(self, root: Optional[TreeNode]) -> int:
        #MAX = 1
        def calculate(root, dept):
            if not root:
                return dept

            return max(calculate(root.left, dept+1), calculate(root.right, dept+1))

        return calculate(root, 0)



Random Note


(k := next(iter(d)), d.pop(k)) will remove the leftmost (first) item (if it exists) from a dict object. And if you want to remove the right most/recent value from the dict

d.popitem()