Leetcode sword finger offer 55 - I. depth of binary tree_ Python
編輯：Python
Enter the root node of a binary tree , Find the depth of the tree . The nodes that pass from the root node to the leaf node （ Containing root 、 Leaf nodes ） A path to a tree , The length of the longest path is the depth of the tree .
for example ：
Given binary tree [3,9,20,null,null,15,7],
3
/ \
9 20
/ \
15 7
Return to its maximum depth 3 .
Tips ：
Total number of nodes <= 10000
Program code
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def maxDepth(self, root: TreeNode) -> int:
if not root:
return 0
return max(self.maxDepth(root.left), self.maxDepth(root.right)) + 1
