LeetCode 1015. Smallest Integer Divisible by K

Problem Statement

impl Solution {
    pub fn smallest_repunit_div_by_k(k: i32) -> i32 {
        let (mut cur, mut ans) = (1, 1);
        if k % 2 == 0 || k  % 5 == 0 {
            return -1;
        }

        while ans <= k {
            if cur % k == 0 {
                return ans;
            }
            cur = (cur * 10 + 1) % k;
            ans += 1;
        }
        return ans;
    }
}