feat: Implemented Morris preorder traversal for Binary tree

data_structures/binary_tree/morris_postorder_traversal.py

@@ -1,170 +0,0 @@
-"""
-Problem Statement: Given a binary perform an postorder traversal using Morris Postorder
-traversal algorithm. (Iterative version of Postorder traversal of tree)
-
-https://www.geeksforgeeks.org/morris-traversal-for-postorder/
-"""
-
-
-class TreeNode:
-    """
-    Class representing a node in a binary tree.
-
-    Attributes:
-    -----------
-    value : int
-        The value stored at the node.
-    left : TreeNode
-        Pointer to the left child node (default is None).
-    right : TreeNode
-        Pointer to the right child node (default is None).
-    """
-
-    def __init__(self, value: int) -> None:
-        self.value = value
-        self.left: TreeNode | None = None
-        self.right: TreeNode | None = None
-
-
-class BinaryTree:
-    """
-    Class representing a binary tree.
-
-    Methods:
-    --------
-    insert(value: int) -> None:
-        Insert a value into the binary tree following binary search tree (BST) rules.
-
-    morris_postorder_traversal() -> List[int]:
-        Perform postorder traversal and return list of node values.
-
-
-    >>> bt = BinaryTree()
-    >>> bt.insert(9)
-    >>> bt.insert(6)
-    >>> bt.insert(10)
-    >>> bt.insert(3)
-    >>> bt.insert(7)
-    >>> bt.insert(12)
-    >>> bt.insert(2)
-    >>> bt.insert(5)
-    >>> bt.insert(4)
-    >>> bt.morris_postorder_traversal()
-    [2, 4, 5, 3, 7, 6, 12, 10, 9]
-
-    """
-
-    def __init__(self) -> None:
-        self.root: TreeNode | None = None
-
-    def insert(self, value: int) -> None:
-        """
-        Insert a value into the binary tree.
-
-        Parameters:
-        -----------
-        value : int
-            The value to be inserted into the binary tree.
-        """
-        if self.root is None:
-            self.root = TreeNode(value)
-        else:
-            self._insert_recursive(self.root, value)
-
-    def _insert_recursive(self, node: TreeNode, value: int) -> None:
-        """
-        Helper function to insert a value recursively into the tree.
-
-        Parameters:
-        -----------
-        node : TreeNode
-            The current node in the binary tree.
-        value : int
-            The value to be inserted.
-        """
-        if value < node.value:
-            if node.left is None:
-                node.left = TreeNode(value)
-            else:
-                self._insert_recursive(node.left, value)
-        elif node.right is None:
-            node.right = TreeNode(value)
-        else:
-            self._insert_recursive(node.right, value)
-
-    def _successor(self, node: TreeNode) -> TreeNode:
-        """
-        Helper Function to return successor of the given node in a binary tree
-
-        Parameters:
-        -----------
-        node : TreeNode
-            A node in the binary tree.
-
-        Returns:
-        --------
-        TreeNode:
-            The successor of the node passed in the parameter
-        """
-        temp_node = node.right
-        while temp_node and temp_node.left and temp_node.left != node:
-            temp_node = temp_node.left
-        assert temp_node is not None, "Successor should not be None"
-        return temp_node
-
-    def morris_postorder_traversal(self) -> list[int]:
-        """
-        Function for postorder traversal using morris postorder traversal.
-
-        Algorithm :
-        ------------
-        First set current node as root node.
-
-        while current node is not empty
-            If the current node has no right child.
-                push the current node to temp.
-                point the current node to its left child
-
-            else.
-                find successor node of the current node.
-                if successor left child points to current node,
-                    remove the link of the left child of successor node.
-                    point the current node to its left child.
-                else,
-                    push the current node to temp.
-                    make the current node as the left child of the successor node.
-                    point current node to its right child.
-
-        Reverse the temp array to get postorder traversaol.
-
-        Returns:
-        --------
-        List[int]:
-            A list of integers representing the postorder traversal.
-
-
-
-        """
-        postorder_traversal = []
-        current_node = self.root
-
-        while current_node:
-            if current_node.right is None:
-                postorder_traversal.append(current_node.value)
-                current_node = current_node.left
-            else:
-                successor_node = self._successor(current_node)
-                if successor_node.left == current_node:
-                    successor_node.left = current_node
-                    current_node = current_node.left
-                else:
-                    postorder_traversal.append(current_node.value)
-                    successor_node.left = current_node
-                    current_node = current_node.right
-        return postorder_traversal[::-1]
-
-
-if __name__ == "__main__":
-    import doctest
-
-    doctest.testmod()