class BiTreeNode: def __init__(self, data=None): self.data = data self.l_child = None self.r_child = None class BiTree(object): def __init__(self, root=None): self.r_child = None self.l_child = None self.root = root @classmethod def createBiTree(cls, order): q = LinkQueue() root = BiTreeNode() print("节点个数") bt.nodeCount(bt.root) print() bt = BiTree(root) q.offer(root) for i in range(len(order)): c = order[i] node = q.peek() if node.l_child is None: newNode = BiTreeNode(c) node.l_child = newNode q.offer(newNode) elif node.r_child is None: newNode = BiTreeNode(c) node.r_child = newNode q.offer(newNode) q.poll() return bt def Order(self, root): q = LinkQueue() q.offer(root) while not q.isEmpty(): p = q.poll() print(p.data, end='') if p.l_child is not None: q.offer(p.l_child) if p.r_child is not None: q.offer(p.r_child) def nodeCount(t): count = 0 if t is not None: count += 1 count += nodeCount(t.l_child) count += nodeCount(t.r_child) return count

代码中存在两个问题：

1. 在createBiTree方法中，先调用了bt.nodeCount方法，再将root节点传入BiTree类的构造方法中，这会导致nodeCount方法中的t参数为None，从而导致程序抛出异常。
2. nodeCount方法应该是BiTree类的方法，而不是独立的函数。因此，应该将nodeCount方法移动到BiTree类中，并将其改为实例方法。

修改后的代码如下：

from queue import Queue

class BiTreeNode:
    def __init__(self, data=None):
        self.data = data
        self.l_child = None
        self.r_child = None

class BiTree(object):
    def __init__(self, root=None):
        self.root = root

    @classmethod
    def createBiTree(cls, order):
        q = Queue()
        root = BiTreeNode()
        bt = BiTree(root)
        q.put(root)
        for i in range(len(order)):
            c = order[i]
            node = q.get()
            if node.l_child is None:
                newNode = BiTreeNode(c)
                node.l_child = newNode
                q.put(newNode)
            elif node.r_child is None:
                newNode = BiTreeNode(c)
                node.r_child = newNode
                q.put(newNode)
        return bt

    def Order(self, root):
        q = Queue()
        q.put(root)
        while not q.empty():
            p = q.get()
            print(p.data, end='')
            if p.l_child is not None:
                q.put(p.l_child)
            if p.r_child is not None:
                q.put(p.r_child)

    def nodeCount(self, t):
        count = 0
        if t is not None:
            count += 1
            count += self.nodeCount(t.l_child)
            count += self.nodeCount(t.r_child)
        return count

修改后的代码中，将nodeCount方法移动到BiTree类中，并将其改为实例方法。同时，将createBiTree方法中的节点计数移动到Order方法中，确保root节点已经被正确初始化。另外，将LinkQueue替换为Python内置的Queue。