104-maximum-depth-of-binary-tree.py

"""
Problem Link: https://leetcode.com/problems/maximum-depth-of-binary-tree/description/

Given a binary tree, find its maximum depth.
The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
Note: A leaf is a node with no children.

Example:

Given binary tree [3,9,20,null,null,15,7],
    3
   / \
  9  20
    /  \
   15   7
return its depth = 3.
"""
# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

class Solution(object):
    def maxDepth(self, root):
        if root == None:
            return 0
        return 1 + max(self.maxDepth(root.left), self.maxDepth(root.right))