1015. Smallest Integer Divisible by K

Given a positive integer k, you need to find the length of the smallest positive integer n such that n is divisible by k, and n only contains the digit 1. Return the length of n. If there is no such n, return -1. Note: n may not fit in a 64-bit signed integer. Example 1: Input: k = 1 Output: 1 Explanation: The smallest answer is n = 1, which has length 1. Example 2: Input: k = 2 Output: -1