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.
# Python 3
# 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 root == None:
return 0
elif root.left == None and root.right == None:
return 1
elif root.left != None and root.right != None:
return max(1 + self.maxDepth(root.left), 1 + self.maxDepth(root.right))
elif root.left:
return 1 + self.maxDepth(root.left)
else:
return 1 + self.maxDepth(root.right)