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.

EasyTechnical

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Implement a function in Python to determine whether there exists a root-to-leaf path in a binary tree such that the sum of node values equals a given target. Return True or False. Handle negative values and empty trees correctly and explain the time/space complexity.

HardTechnical

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Compare using plain binary search trees versus KD-trees and ball trees for nearest-neighbor-like lookups in ML applications. Discuss dimensionality, tree balance, search pruning effectiveness, and when a BST is inappropriate. Provide examples and recommend alternatives for medium to high dimensional feature spaces.

EasyTechnical

0 practiced

Implement an inorder traversal for a binary tree in Python that returns a list of node values in left-root-right order. Your function should accept the root node where nodes are defined as class TreeNode with attributes .val, .left, and .right. Use a recursive approach that runs in O(n) time and O(h) space (call stack), and explain in a short comment why the traversal produces a sorted list when the input is a valid BST.

HardTechnical

0 practiced

Prove that an inorder traversal of a binary search tree yields elements in non-decreasing (sorted) order. Include assumptions about duplicate handling and comparator consistency and explain how the proof changes when duplicates are allowed only on one side.

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.

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