CodingHardcod-g793

Subject Constraint searchLevel Senior–Staff~35 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given a positive integer `n`, return the count of integers in the inclusive range [1, n] that have at least one repeated digit. For example for n = 20 only the number 11 qualifies, so the answer is 1. 1 <= n <= 1000000000.

Implement

num_dup_digits_at_most_n(n: int) → int

Examples

in[20]out1

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.