找到一个数字的 K 美丽值

/*
 * Problem Statement:
 * Given an integer num and an integer k, return the k-beauty of num.
 * The k-beauty is defined as the number of substrings of num that have a length of k
 * and are divisible by num. Leading zeros are allowed in substrings.
 * However, a substring with value 0 is not considered as divisible.
 */
import java.util.stream.IntStream;
public class Solution {
    public int divisorSubstrings(int num, int k) {
        String numStr = String.valueOf(num);
        return (int) IntStream.range(0, numStr.length() - k + 1)
            .mapToObj(i -> numStr.substring(i, i + k))
            .mapToInt(Integer::parseInt)
            .filter(subNum -> subNum != 0 && num % subNum == 0)
            .count();
    }
}