检查树是否为镜像

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

def isMirror(root1, root2):
    # 如果两个树都为空，则为镜像
    if root1 is None and root2 is None:
        return True
    # 如果有一个树为空，则不为镜像
    if root1 is None or root2 is None:
        return False
    # 比较当前节点的值是否相等，并递归比较左右子树
    return (root1.val == root2.val) and isMirror(root1.left, root2.right) and isMirror(root1.right, root2.left)

def isSymmetric(root):
    if root is None:
        return True
    return isMirror(root.left, root.right)

from collections import deque

def isSymmetric(root):
    if root is None:
        return True
    queue = deque()
    queue.append(root.left)
    queue.append(root.right)
    while queue:
        node1 = queue.popleft()
        node2 = queue.popleft()
        if node1 is None and node2 is None:
            continue
        if node1 is None or node2 is None or node1.val != node2.val:
            return False
        queue.append(node1.left)
        queue.append(node2.right)
        queue.append(node1.right)
        queue.append(node2.left)
    return True