1015.py

'''
Given a positive integer K, you need find 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.

 

Example 1:

Input: 1
Output: 1
Explanation: The smallest answer is N = 1, which has length 1.
Example 2:

Input: 2
Output: -1
Explanation: There is no such positive integer N divisible by 2.
Example 3:

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

class Solution(object):
    def smallestRepunitDivByK(self, K):
        """
        :type K: int
        :rtype: int
        """
        length, value = 0, 0
        for no_one in range(100000):
            value = (10*value + 1)%K
            length += 1
            if value == 0:
                return length
        return -1