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Step 47

curriculum/challenges/english/blocks/learn-tree-traversal-by-building-a-binary-search-tree/65d8a8773c816a273653fd0e.md

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--description--

Finally, after your else clause, return the current node.

--hints--

You should return the current node after the else clause.

js
({ test: () => assert.match(code, /^(\s+)else\s*:.+?^\1return\s+node/ms) })

--seed--

--seed-contents--

py

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)

--fcc-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) 
            node.right = self._delete(node.right, node.key)

--fcc-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))