CodingHardcod-g406

Subject Gcd lcmLevel Senior–Staff~35 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given a list of positive integers (length 1 to 2e5, each 1 <= x <= 1e9), return the length of the longest contiguous subarray whose GCD is strictly greater than 1. If no such subarray exists, return 0. A single element x > 1 counts as a length-1 subarray. The O(n^2) approach is too slow; aim for O(n log(maxval)).

Implement

longest_gcd_subarray(nums: list[int]) → int

Examples

in[[2,4,6,3,9,12]]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.