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Binary Trees and Binary Search Trees Questions

Focuses on tree data structures, specifically binary trees and binary search trees. Candidates should understand node relationships, common traversals including in order, pre order, post order, and level order, and be able to implement traversals both recursively and iteratively. Cover binary search tree properties and operations including search, insertion, deletion, validation of binary search tree property, and finding the lowest common ancestor. Include problems on tree paths, height and balance calculations, serialization and deserialization, checking and restoring balance at a high level, and use cases in system design. Emphasize complexity analysis, recursion versus iterative solutions using stacks or queues, and handling edge cases such as duplicate keys and degenerate trees.

HardTechnical
0 practiced
Design an augmented BST that stores subtree sums at each node to support O(log n) queries for the sum of values in any key range [a, b]. Describe how to maintain these sums on insert/delete and provide pseudocode for the range-sum query using augmented data in the nodes.
HardTechnical
0 practiced
Describe how to implement a persistent (immutable, versioned) BST to support versioned snapshots for A/B testing of feature transformations in a model pipeline. Explain path-copying, memory overhead per update, how queries use version roots, and trade-offs compared to copying full trees or using logs.
MediumTechnical
0 practiced
Analyze the time and space complexity differences between recursive and iterative tree traversals (inorder) for balanced vs skewed trees. Include worst-case call stack depth, auxiliary data structure sizes, and the impact on languages like Python without tail-call elimination. Provide recommendations for production ML code.
MediumTechnical
0 practiced
Design a compact preorder-based serialization for a binary tree that uses a single-character null marker and minimal separators. Implement serialize(root) and deserialize(s) in Python, and compare size/performance tradeoffs with level-order serialization when transmitting model trees between microservices.
HardTechnical
0 practiced
Given an unbalanced BST used in production that is causing latency spikes, propose algorithmic and operational mitigations: include immediate short-term fixes and long-term design changes (e.g., periodic rebalancing, background rebuilding, switching to balanced trees). Describe monitoring metrics you would add to detect reoccurrence.

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