Maximum Depth of Binary Tree

Memorized from my COMPSCI 2C03 notes haha.

class Solution:
    def maxDepth(self, root: Optional[TreeNode]) -> int:
        if not root:
            return 0

        return max(self.maxDepth(root.right), self.maxDepth(root.left)) + 1

This function recursively calls height until we reach the traversal of the null nodes. ‘height()’ will return a value, so that is used in the outer recursive call as a value as seen below.