CodingMediumcod-g049

Subject Binary treesLevel Mid–Senior~25 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

You are given a complete binary tree as a level-order array `level` (no gaps; every level except possibly the last is full and the last level is filled left to right). Count the total number of nodes. Aim for better than O(n): a complete tree of n nodes admits an O(log^2 n) count. `0 <= len(level) <= 100000`.

Implement

count_complete_nodes(level: list[int]) → int

Examples

in[[1,2,3,4,5,6]]out6

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.