CodingMediumcod-g068

Subject Balanced treesLevel Mid–Senior~20 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given a binary tree as a level-order array `arr` (null for missing), return True if it is height-balanced — for every node, the heights of its two subtrees differ by at most 1 — and False otherwise. An empty tree is balanced. `0 <= node count <= 50000`.

Implement

is_balanced(arr: list[int]) → bool

Examples

in[[3,9,20,null,null,15,7]]outtrue

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.