CodingHardcod-g067

Subject Lowest common ancestorLevel Senior–Staff~30 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given a binary tree as a level-order array `arr` (null for missing), return the value of the lowest common ancestor of all the DEEPEST leaves (the leaves at maximum depth). If there is a single deepest leaf, it is its own answer. The tree is non-empty with distinct values. `1 <= node count <= 10000`.

Implement

lca_deepest_leaves(arr: list[int]) → int

Examples

in[[3,5,1,6,2,0,8,null,null,7,4]]out2

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.