2269 - Find the K-Beauty of a Number.

Easy

The k-beauty of an integer num is defined as the number of substrings of num when it is read as a string that meet the following conditions:

• It has a length of k.

• It is a divisor of num.

Given integers num and k, return the k-beauty of num.

Note:

• Leading zeros are allowed.

• 0 is not a divisor of any value.

A substring is a contiguous sequence of characters in a string.

Example 1:

Input: num = 240, k = 2

Output: 2

Explanation: The following are the substrings of num of length k:

• "24" from "240": 24 is a divisor of 240.

• "40" from "240": 40 is a divisor of 240.

Therefore, the k-beauty is 2.

Example 2:

Input: num = 430043, k = 2

Output: 2

Explanation: The following are the substrings of num of length k:

• "43" from "430043": 43 is a divisor of 430043.

• "30" from "430043": 30 is not a divisor of 430043.

• "00" from "430043": 0 is not a divisor of 430043.

• "04" from "430043": 4 is not a divisor of 430043.

• "43" from "430043": 43 is a divisor of 430043.

Therefore, the k-beauty is 2.

Constraints:

• <code>1 <= num <= 10⁹</code>

• 1 <= k <= num.length (taking num as a string)