This question evaluates proficiency with sliding-window techniques and breadth-first search on trees, measuring competencies in windowed string/state management, level-order traversal, and use of core data structures; it is categorized under Coding & Algorithms and emphasizes practical implementation skills.

Solve a typical medium-level sliding-window problem (e.g., longest substring without repeating characters). LeetCode 102. Binary Tree Level Order Traversal
https://leetcode.com/problems/binary-tree-level-order-traversal/description/