Return the Minimum-Sum Root-to-Leaf Path
Company: Meta
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: hard
Interview Round: Onsite
Overview: Find the minimum-sum root-to-leaf path in a binary tree while handling negative values, empty input, and a deterministic leftmost tie-break. Your approach must remain safe and efficient for a deeply skewed tree with up to 100,000 nodes.