在Python中寻找二叉树的深度

class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

def maxDepth(root):
    if root is None:
        return 0
    left_depth = maxDepth(root.left)
    right_depth = maxDepth(root.right)
    return max(left_depth, right_depth) + 1

from collections import deque

def maxDepth(root):
    if root is None:
        return 0
    queue = deque()
    queue.append(root)
    depth = 0
    while queue:
        size = len(queue)
        for _ in range(size):
            node = queue.popleft()
            if node.left:
                queue.append(node.left)
            if node.right:
                queue.append(node.right)
        depth += 1
    return depth