Python 的二叉树，getRoot 没有 return 根

Question

我一直在查看这个二叉树代码以了解它的作用：

class BinaryTree:
    def __init__(self):
        self.root = None
        self.size = 0

    # Insert element e into the binary search tree
    # Return True if the element is inserted successfully 
    def insert(self, e):
        if self.root == None:
            self.root = self.createNewNode(e) # Create a new root
        else:
            # Locate the parent node
            parent = None
            current = self.root
            while current != None:
                if e < current.element:
                    parent = current
                    current = current.left
                elif e > current.element:
                    parent = current
                    current = current.right
                else:
                    return False # Duplicate node not inserted

            # Create the new node and attach it to the parent node
            if e < parent.element:
                parent.left = self.createNewNode(e)
            else:
                parent.right = self.createNewNode(e)

        self.size += 1 # Increase tree size
        return True # Element inserted

    # Create a new TreeNode for element e
    def createNewNode(self, e):
        return TreeNode(e)

    # Return the size of the tree
    def getSize(self):
        return self.size

    # Return true if the tree is empty
    def isEmpty(self):
        return self.size == 0
        
    # Remove all elements from the tree
    def clear(self):
        self.root == None
        self.size == 0

    # Return the root of the tree
    def getRoot(self):
        return self.root

class TreeNode:
    def __init__(self, e):
        self.element = e
        self.left = None  # Point to the left node, default None
        self.right = None # Point to the right node, default None

如果我执行以下代码：

tree = BinaryTree()
tree.insert("500")
print(tree.getRoot)
print(tree.getRoot())

结果：

<bound method BinaryTree.getRoot of <__main__.BinaryTree object at 0x036E1E68>>
<__main__.TreeNode object at 0x036FA1F0>

即使它是根，我也不会取回字符串“500”。 getRoot 函数中是否缺少某些内容？我找不到导致函数无法 return 字符串的原因。

Answer 1

tree.getRoot 是 BinaryTree 对象的一个方法。 tree.getRoot() 正在调用该方法，它 returns 是一个 TreeNode 对象。如果你想得到“500”，你应该得到它的 element 属性。

所以你可以试试下面的代码：

tree = BinaryTree()
tree.insert("500")
print(tree.getRoot().element)

打印

Python 的二叉树，getRoot 没有 return 根

Binary Tree for Python, getRoot does not return root

python

binary-tree

class

object