CodingMediumcod-g940

Subject Prefix sumLevel Mid–Senior~25 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given an integer array and an integer k, return the number of contiguous subarrays whose sum is divisible by k. The array has at most 30000 elements with values in [-10000, 10000]; k is a positive integer up to 10000. Note that negative prefix sums must be handled with care for the modulo.

Implement

subarrays_div_by_k(arr: list[int], k: int) → int

Examples

in[[4,5,0,-2,-3,1],5]out7

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.