CodingHardcod-g640

Subject Number theoryLevel Senior–Staff~35 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Count how many integers in the inclusive range [1, n] are divisible by their own digit sum (Harshad / Niven numbers). For example 12 qualifies because 12 is divisible by 1+2=3. Constraints: 1 <= n <= 200000. Return the count.

Implement

count_harshad(n: int) → int

Examples

in[12]out11

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.