以下函数check()用于判断一棵二叉树是否为（ ）。from collections import dequeclass TreeNode:def __init__(self, val=0, left=None, right=None):self.val = valself.left = leftself.right = rightdef check(root):if not root:return Trueq = deque()q.append(root)has_null = Falsewhile q:cur = q.popleft()if not cur:has_null = Trueelse:if has_null:return Falseq.append(cur.left)q.append(cur.right)return True
A. 满二叉树
B. 完全二叉树
C. 二叉搜索树
D. 平衡二叉树
正确答案：B
试卷来源：202512 CCF-GESP编程能力等级认证Python六级真题