# 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:
• `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)

### 解題

func divisorSubstrings(num int, k int) int {
s := strconv.Itoa(num)
ans := 0
for i:=0; i<len(s)-k+1; i++ {
b, err := strconv.Atoi(s[i: i+k])
if err==nil && b!= 0{
if num % b == 0 { ans++ }
}
}
return ans
}