遍歷二進制搜索樹Python

Question

我正在努力遍歷二叉搜索樹，我認為我的代碼正確，但是仍然遇到以下錯誤。

C:\Python33\python.exe "C:/Users/koopt_000/Desktop/College/Sophomore Semester 2/Computer Science 231/Chapter7/Test.py"
Traceback (most recent call last):
  File "C:/Users/koopt_000/Desktop/College/Sophomore Semester 2/Computer Science 231/Chapter7/Test.py", line 16, in <module>
    print(BST.preOrder(tree))
TypeError: preOrder() missing 1 required positional argument: 'tree'

Process finished with exit code 1

我正在嘗試打印我的樹的預定順序，但它不想工作，這是我的代碼。

class TreeNode(object):

    def __init__(self, data = None, left=None, right=None):

        self.item = data
        self.left = left
        self.right = right

    def __str__(self):
        return str(self.item)


#------------------------------------------------------------

from TreeNode import TreeNode


class BST(object):

    #------------------------------------------------------------

    def __init__(self):



        self.root = None
        self.size = 0

    #------------------------------------------------------------

    def preOrder(self, tree):
        if tree is None:
            pass
        else:
            print(tree.item)
            preOrder(tree.left)
            preOrder(tree.right)

    def postOrder(self, root):
        if root is None:
            pass
        else:
            self.postOrder(root.left)
            self.postOrder(root.right)
            print(root.item)

    def inOrder(self, root):
        if root is None:
            pass
        else:
            self.inOrder(root.left)
            print(root.item)
            self.inOrder(root.right)

這是我的測試代碼：

from BinarySearchTree import BST
from TreeNode import TreeNode

tree = TreeNode(1,
                TreeNode(2,
                         TreeNode(4,
                                  TreeNode(7,None,None),
                                  None),
                         TreeNode(5, None, None)),
                TreeNode(3,
                         TreeNode(6,
                                  TreeNode(8, None, None),
                                  TreeNode(9, None, None)),
                         None))

print(BST.preOrder(tree))

我知道它必須與我做一些事情，在我的打印聲明中放入一些“自我”的內容，但是我很沮喪，目前我的大腦無法正常運行。 有任何想法嗎？

Answer 1

進行一些更改對我來說很好。

bst.py：

class TreeNode(object):

    def __init__(self, data = None, left=None, right=None):

        self.item = data
        self.left = left
        self.right = right

    def __str__(self):
        return str(self.item)


#------------------------------------------------------------


class BST(object):

    #------------------------------------------------------------

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

    #------------------------------------------------------------

    def preOrder(self, tree):
        if tree is None:
            pass
        else:
            print(tree.item)
            self.preOrder(tree.left)
            self.preOrder(tree.right)

    def postOrder(self, root):
        if root is None:
            pass
        else:
            self.postOrder(root.left)
            self.postOrder(root.right)
            print(root.item)

    def inOrder(self, root):
        if root is None:
            pass
        else:
            self.inOrder(root.left)
            print(root.item)
            self.inOrder(root.right)

東西

from bst import BST
from bst import TreeNode

tree = TreeNode(1,
                TreeNode(2,
                         TreeNode(4,
                                  TreeNode(7,None,None),
                                  None),
                         TreeNode(5, None, None)),
                TreeNode(3,
                         TreeNode(6,
                                  TreeNode(8, None, None),
                                  TreeNode(9, None, None)),
                         None))

a = BST()

print(a.preOrder(tree))

輸出：

bob@squids:~/Desktop$ python something.py
1
2
4
7
5
3
6
8
9
None