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:

• 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
}