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Tree•Pattern: BFS•Medium

Binary tree level-order traversal (BFS)

Problem Intuition & Objective

Return node values level by level using a queue-based BFS.

Time ComplexityO(n)
Optimal
Space ComplexityO(n)
Memory Bounds
Optimal Algorithmic Approach

BFS with level-size tracking.

Core Invariants & Edge Cases

  • Enqueue the root; while queue non-empty process all nodes of current level
  • Record size of queue at start of each level to know level boundary
  • Collect results per level into a list of lists
Previous ProblemSliding window maximum using a dequeNext Problem Validate a Binary Search Tree

System Design & Architecture Roadmap

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