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.
求二叉树的层数。
637.Average of Levels in Binary Tree；......
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:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def maxDepth(self, root):
"""
:type root: TreeNode
:rtype: int
"""
if not root:
return 0
ans = []
node = [root]
while node:
ans.append([i.val for i in node])
curr = []
for each in node:
if each.left:
curr.append(each.left)
if each.right:
curr.append(each.right)
node = curr
return len(ans)