Walk through nodes in linked list python

Question

I'm set to do a binary tree search like the one here. I have a problem to set the nodes correctly.

The problem: When a new node should be created, the root node seems to be overwriten. First time

Bintree.put(newValue)

is called a new node is created at the Bintree.root. The second time, the root node seems to be overwriten in the functioncall Bintree.put(newValue).

Does these lines below change the root node when it is executed?

node = root
node = node.left # Left is a node below node
node = Node()

The lines below is the code for my program.

# Node for binary tree
class Node():
def __init__(self):
    self.data = None
    self.left = None
    self.right = None

class Bintree:
    def __init__(self):
            self.root = None

        def put(self, newvalue):
            '''Sends the new value into the correct position in the Bintree
            :param newvalue: The data that's sent to storage'''
            self.root = push(self.root, newvalue)

def push(root, value):
    # This function puts the value in the correct position in the bintree
    # Not to be used by user.
    node = root

    while node is not None:
        if node.data < value:
            node = node.left
        else:
            node = node.right

    node = Node()
    node.value = value

    return node

Boendal · Accepted Answer · 2017-01-24 10:56:48Z

2

Yeah you're right I screwed it up a little bit.

class Node():
    def init(self):
        self.data = None
        self.left = None
        self.right = None

class Bintree:
    def init(self):
        self.root = None

    def put(self, newvalue):
        '''Sends the new value into the correct position in the Bintree
        :param newvalue: The data that's sent to storage'''
        if self.root is None:
            self.root = Node()
            self.root.data = newvalue
        else:
            self.push(self.root, newvalue)

    def push(self, node, value):
        # This function puts the value in the correct position in the bintree
        # Not to be used by user.

        if value < node.data:
            if node.left is not None:
                self.push(node.left,value)
            else:
                node.left = Node()
                node.left.data = value
        else:
            if node.right is not None:
                self.push(node.right,value)
            else:
                node.right = Node()
                node.right.data = value

I did it from scratch with recursive. It's simpler. Of course it didn't work because in your first attempt you always set root to none and in the second you only update root all the time (my bad)

edited Jan 24, 2017 at 10:56

answered Jan 24, 2017 at 10:11

Boendal

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1 Comment

user3061876 Over a year ago

Changed the thing you commented. Put if I try the following: bintree = Bintree() bintree.put(12) bintree.put(13) I get error when executing bintree.put(13) that node exists, but node.data does not have any value in the loop in push.

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