python3(递归，层次遍历)

方法一:递归

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    def TreeDepth(self, pRoot):
        # write code here
        if not pRoot:
            return 0
        right = left = 0
        if pRoot.left:
            left = self.TreeDepth(pRoot.left)
        if pRoot.right:
            right = self.TreeDepth(pRoot.right)
        return max([left,right])+1

方法二:层次遍历，每经历一层， count+=1

# -*- coding:utf-8 -*-
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
class Solution:
    def TreeDepth(self, pRoot):
        # write code here
        count = 0
        if not pRoot:
            return 0
        now_layer = [pRoot]
        next_layer = []
        while now_layer:
            for i in now_layer:
                if i.left:
                    next_layer.append(i.left)
                if i.right:
                    next_layer.append(i.right)
            count+=1
            now_layer,next_layer = next_layer,[]
        return count