2269. Find the K-Beauty of a Number

QUESTION:

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:

``````1 <= num <= 109
1 <= k <= num.length (taking num as a string)
``````

SOLUTION:

``````class Solution {
func divisorSubstrings(_ num: Int, _ k: Int) -> Int {
var result: Int = 0
var arr:[Character] = Array(String(num))
for index in 0...arr.count - k {
var tmpString:String = ""
for j in index...index + k - 1 {
tmpString += String(arr[j])
}
var tmpNum:Int = Int(tmpString)!
if tmpNum != 0 && num % tmpNum == 0 {
result += 1
}
}
return result
}
}
``````