Code RoomNumbers with repeated digits
HardPrep Room Coding #1356

Numbers with repeated digits

CodingAlgorithms & data structuresSenior–Staff~35 min

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.

0:00 of about 35 min
InputExpectedGot
[20]1not run yetsample