Learn Tree Traversal by Building a Binary Search Tree - Step 46

Python
1

Tell us what’s happening:

I don’t understand what I am doing wrong, I am not fully understanding the instruction.

Your code so far


class TreeNode:

    def __init__(self, key):
        self.key = key
        self.left = None
        self.right = None

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

class BinarySearchTree:

    def __init__(self):
        self.root = None

    def _insert(self, node, key):
        if node is None:
            return TreeNode(key)

        if key < node.key:
            node.left = self._insert(node.left, key)
        elif key > node.key:

            node.right = self._insert(node.right, key)
        return node

    def insert(self, key):
        self.root = self._insert(self.root, key)
        
    def _search(self, node, key):
        if node is None or node.key == key:
            return node
        if key < node.key:
            return self._search(node.left, key)
        return self._search(node.right, key)
    
    def search(self, key):
        return self._search(self.root, key)


# User Editable Region

    def _delete(self, node, key):
        if node is None:
            return node
        if key < node.key:
            node.left = self._delete(node.left, key)
        elif key > node.key:
            node.right = self._delete(node.right, key)
        else:
            if node.left is None:
                return node.right
            elif node.right is None:
                return node.left

            node.key = self._min_value(node.right)
        self._delete(node.rigt,node.key)
            

# User Editable Region

    def _min_value(self, node):
        while node.left is not None:
            node = node.left

bst = BinarySearchTree()

nodes = [50, 30, 20, 40, 70, 60, 80]

for node in nodes:
    bst.insert(node)

# print('Search for 80:', bst.search(80))

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Challenge Information:

Learn Tree Traversal by Building a Binary Search Tree - Step 46

2

Call the _delete method recursively with node.right and node.key as the arguments.

You almost did this. Check the arguments because there’s a typo.

Assign the return value of the _delete() call to the right child of the current node.

You missed the part of assigning the value returned by the function call to the right child of the current node.

Also, all of this should be done inside the else clause.