Leetcode2062 solution

Solution.java

// https://leetcode.com/problems/count-vowel-substrings-of-a-string/
// https://youtu.be/hGH_Z4_jMBI
///
class Solution {
    public int countVowelSubstrings(String word) {
        int n = word.length();
        int[] fq = new int[26];
        int k = 0; int l = 0;
        int res = 0;
        for (int r = 0; r < n; r++) {
            char ch = word.charAt(r);
            if (ch == 'a' || ch == 'o' || ch == 'e' || ch == 'i' || ch == 'u') {
                fq[ch-'a']++;
                if (fq[(int)'a'-'a']>0 && fq[(int)'o'-'a']>0
                    && fq[(int)'e'-'a']>0 && fq[(int)'i'-'a']>0
                    && fq[(int)'u'-'a']>0
                ) {
                    while (fq[word.charAt(k)-'a']>1) {
                        fq[word.charAt(k)-'a']--;
                        k++;
                    }
                    res += (k-l+1);
                }
            } else {
                fq = new int[26];
                k = r+1; 
                l = r+1;
            }
        }
        return res;
    }
}