#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
#
# 
# @param pRoot TreeNode类 
# @return int整型
#
class Solution:
    def TreeDepth(self , pRoot: TreeNode) -> int:
        # write code here
        if not pRoot:
            return 0
        res = 1
        queTree = [pRoot]
        while queTree:
            temp = []
            for node in queTree:
                if node.left:
                    temp.append(node.left)
                if node.right:
                    temp.append(node.right)
            queTree  = temp
            if queTree == []:
                res = res
            else:
                res += 1
        return res

采用广度优先遍历,遍历二叉树的每一层,每层若不为空则计数器累加1。