Basic Framework
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LeetCode Card 267 — Binary Search Trees / Assess

Binary Search Trees — BASIC step map

Pattern signal

This pattern usually appears when the prompt involves ordered tree properties, rank queries, or pruning based on node value. Validate BST, Kth Smallest Element in a BST, Lowest Common Ancestor of a BST, and range queries are the usual forms.

Patterns are shortcuts, not substitutes for reasoning.

What Assess means here

In BASIC, the Assess step is where you compare the viable data structures or traversals and decide what complexity target fits. For Binary Search Trees, that matters because the pattern only becomes useful once the candidate is explicit about what is being tracked, reduced, or preserved.

Interview move

A strong move is to compare plausible approaches before committing. In this pattern family, say out loud what representation makes the problem easier: the map entry, the pointer invariant, the recursion contract, the queue contents, or the DP state. That keeps the implementation attached to a reason.

Common miss

The miss is treating a BST like a generic tree and ignoring the ordering information that should prune work. BASIC reduces that risk because the stage sequence forces you to earn the implementation instead of jumping straight into it.

BASIC prompt

“Given that this looks like Binary Search Trees, what is the simplest way to compare the viable data structures or traversals and decide what complexity target fits?”

The real skill here
Assessment is comparison, not selection. Strong candidates explore at least two paths before committing. They don't just say 'I'll use a hash map' — they explain why the alternative (sorting, brute force, different data structure) is worse for this specific problem. That comparison is the signal.

References

S10 S12 S13

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