Tree Traversal in Python | Dataford Interview Questions

HashedIn by Deloitte QA automation workflows may need deterministic traversal results when validating hierarchical test configurations. Given a binary tree, return its pre-order, in-order, and post-order traversals without recursively walking the tree.

Formal Specification

Implement tree_traversals(root). The input root is either None or a nested dictionary with this structure: {"value": integer, "left": node_or_None, "right": node_or_None}. Return a dictionary with three keys: "preorder", "inorder", and "postorder", each containing a list of node values.

Use an iterative algorithm based on an explicit stack. The solution must preserve traversal ordering and should support highly unbalanced trees that may exceed Python's recursion limit.

Constraints

The tree contains 0 to 100,000 nodes.
Each node value is an integer between -10^9 and 10^9.
Each node has at most one left child and one right child.
The input is a valid binary tree.

Function Signature

def tree_traversals(root):

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