Binary search tree with python generators

Binary search trees are a fundamental data structure in computer science. They allow for efficient searching, insertion, and deletion of elements. In this article, we will explore different ways to implement a binary search tree using Python generators.

Option 1: Recursive Approach

The first option is to implement the binary search tree using a recursive approach. We can define a generator function that takes a node as input and yields the values in the tree in sorted order.

class Node:
    def __init__(self, value):
        self.value = value
        self.left = None
        self.right = None

def inorder_traversal(node):
    if node:
        yield from inorder_traversal(node.left)
        yield node.value
        yield from inorder_traversal(node.right)

In this code snippet, we define a Node class that represents a node in the binary search tree. The inorder_traversal function is a generator function that performs an inorder traversal of the tree. It recursively yields the values in sorted order by traversing the left subtree, yielding the current node’s value, and then traversing the right subtree.

Option 2: Iterative Approach

The second option is to implement the binary search tree using an iterative approach. We can use a stack to simulate the recursive calls in the previous approach.

class Node:
    def __init__(self, value):
        self.value = value
        self.left = None
        self.right = None

def inorder_traversal(node):
    stack = []
    current = node

    while True:
        if current:
            stack.append(current)
            current = current.left
        elif stack:
            current = stack.pop()
            yield current.value
            current = current.right
        else:
            break

In this code snippet, we define a Node class similar to the previous approach. The inorder_traversal function uses a stack to keep track of the nodes to visit. It starts with the leftmost node and iteratively traverses the tree, yielding the values in sorted order.

Option 3: Morris Traversal

The third option is to use Morris traversal, which allows for an inorder traversal of a binary tree without using a stack or recursion. It achieves this by modifying the tree structure temporarily.

class Node:
    def __init__(self, value):
        self.value = value
        self.left = None
        self.right = None

def inorder_traversal(node):
    current = node

    while current:
        if not current.left:
            yield current.value
            current = current.right
        else:
            predecessor = current.left

            while predecessor.right and predecessor.right != current:
                predecessor = predecessor.right

            if not predecessor.right:
                predecessor.right = current
                current = current.left
            else:
                predecessor.right = None
                yield current.value
                current = current.right

In this code snippet, we define a Node class similar to the previous approaches. The inorder_traversal function uses the Morris traversal technique to yield the values in sorted order. It modifies the tree structure temporarily by creating threaded links between nodes.

After exploring these three options, it is clear that the recursive approach (Option 1) is the most straightforward and intuitive. It uses Python generators to yield the values in sorted order without the need for additional data structures. The iterative approach (Option 2) and Morris traversal (Option 3) are more complex and require additional bookkeeping. Therefore, the recursive approach is the better option for implementing a binary search tree using Python generators.

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10 Responses

    1. Option 3 might seem fancy, but its not just about the effort. Morris Traversal offers efficiency and simplicity, making it a valuable tool in certain scenarios. Its worth exploring different options to find what works best for you. 🌟

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