python针对二叉树检查值，空输出

Question

Been stuck on this problem now for a long time and its time to get some help. Almost everything works. It read the files and input the data and so on.. The program dont give me any output and something is wrong with the last if statments.. The three last rows is

root1.put(word1)
if root.exists(word1):
    print(word1, end = " ")

It puts in the value in the tree. and then it will check against the first tree if the value "word1" is already in that tree if that is true it will print out the word, if not go on. This program just give me an empty output. Is there any chance someone can see the problem? The other class file looks almost the same just without the 1's to all variables/para..

Class file (root1)

class BintreeEN:
    def __init__(self, data1):
        self.left1 = None 
        self.right1 = None 
        self.data1 = data1

    def put(self, data1):
        if data1 < self.data1:
            if self.left1 is None:
                self.left1 = BintreeEN(data1)
            else:
                self.left1.put(data1)
        else:
            if self.right1 is None:
                self.right1 = BintreeEN(data1)
            else:
                self.right1.put(data1)

    def write(self):
        if self.left1: 
            self.left1.write()
        print(self.data1) 
        if self.right1: 
            self.right1.write()

    def exists(self, data1):
        if data1 < self.data1:
            if self.left1 is None:
                return None, None
            return self.left1.exists(data1)
        elif data1 > self.data1:
            if self.right1 is None:
                return None, None
            return self.right1.exists(data1)
        else:
            return self.data1

Program file

#first tree
root = Bintree("root")
with open("word3.txt", "r", encoding = "utf-8") as file:
    for row in file:
        word = row.strip()
        checklist = root.exists(word)
        if checklist == word:
            pass
        else:
            root.put(word)
#second tree
root1 = BintreeEN("root1")
with open('engelska.txt','r', encoding = "utf-8") as f:
    for row in f:
        onerow = row.split()
        for rowz in onerow:
            word1 = rowz.strip()
            #HERE IT something thats wrong...
            if root1.exists(word1):
                pass
            else:
                root1.put(word1)
                if root.exists(word1): #Check if value is in the first tree
                    print(word1, end = " ")

Answer 1

Your exists() method returns a True value, always . Your .put() is never called, as the first if is always true instead:

if root1.exists(word1):
    pass

Your .exists() method returns (None, None) in case the value does not exist in the tree, and a non-empty tuple is always True:

>>> if (None, None):
...     print 'A tuple is considered True if not empty'
... 
A tuple is considered True if not empty

Return simply just None instead, not a tuple:

def exists(self, data1):
    if data1 < self.data1:
        if self.left1 is None:
            return None
        return self.left1.exists(data1)
    elif data1 > self.data1:
        if self.right1 is None:
            return None
        return self.right1.exists(data1)
    else:
        return self.data1

or, by using the short-circuiting nature of and and the fact that return exits the function immediately:

def exists(self, data1):
    if data1 < self.data1:
        return self.left1 and self.left1.exists(data1)
    if data1 > self.data1:
        return self.right1 and self.right1.exists(data1)
    return self.data1

With this change your binary tree works fine:

>>> tree = BintreeEN('foo')
>>> tree.exists('foo')
'foo'
>>> tree.exists('bar')
>>> tree.put('bar')
>>> tree.exists('bar')
'bar'