#3790

Smallest All-Ones Multiple

medium · 46.9% accepted · 93 likes · top 31%

hash table · math

⊣ practice⊣ open on leetcode ↗

Description

You are given a positive integer k.

Find the smallest integer n divisible by k that consists of only the digit 1 in its decimal representation (e.g., 1, 11, 111, ...).

Return an integer denoting the number of digits in the decimal representation of n. If no such n exists, return -1.

Solution