# -*- coding:utf-8 -*-

# 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):

"""

:type root: TreeNode

:rtype: int

"""

stack=[]

res=0

if root:

stack.append(root)

while(stack):

for i in range(len(stack)):

node=stack.pop(0)

if node.left:

stack.append(node.left)

if node.right:

stack.append(node.right)

res += 1

return res

#递归解法

def maxDepth1(self, root):

"""

:type root: TreeNode

:rtype: int

"""

if not root:

return 0

left_depth=self.maxDepth1(root.left)

right_depth=self.maxDepth1(root.right)

max=left_depth if left_depth>right_depth else right_depth

max += 1

return max

if __name__ == "__main__":

node1=TreeNode(3)

node2=TreeNode(9)

node3=TreeNode(20)

node4 = TreeNode(15)

node5 = TreeNode(7)

node6 = TreeNode(2)

node7 = TreeNode(3)

node1.left=node2

node1.right = node3

# node2.left = node4

# node2.right = node5

node3.left = node4

node3.right = node5

r=Solution().maxDepth1(node1)

print r