1015. Smallest Integer Divisible by K

Medium

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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
Explanation: There is no such positive integer n divisible by 2.

Example 3:

Input: k = 3
Output: 3
Explanation: The smallest answer is n = 111, which has length 3.

Constraints:

• 1 <= k <= 105

class Solution:
    def smallestRepunitDivByK(self, k: int) -> int:
        num = 0
        for i in range(k):
            num = num*10 + 1
            if num%k == 0:
                return len(str(num))
        return -1