CodingMediumcod-g066

Subject Lowest common ancestorLevel Mid–Senior~25 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given a general binary tree as a level-order array `arr` (null for missing) and two distinct-or-equal values `a` and `b` that are both present, return the number of edges on the shortest path between them. If `a == b` the distance is 0. Values are distinct across the tree. `1 <= node count <= 20000`.

Implement

distance_between_nodes(arr: list[int], a: int, b: int) → int

Examples

in[[1,2,3,4,5,6,7],4,7]out4

What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

Learn the concepts

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.