2559. Count Vowel Strings in Ranges 

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class Solution {
    private static final Set<Character> VOWEL_CHAR_SETS = new HashSet<>(Arrays.asList('a', 'e', 'i', 'o', 'u'));

    public int[] vowelStrings(String[] words, int[][] queries) {
        int[] prefixCounts = new int[words.length + 1];
        for (int i = 1; i < prefixCounts.length; i++) {
            prefixCounts[i] = prefixCounts[i - 1] + (ifVowelString(words[i - 1]) ? 1 : 0);
        }

        int[] res = new int[queries.length];
        for (int i = 0; i < queries.length; i++) {
            res[i] = prefixCounts[queries[i][1] + 1] - prefixCounts[queries[i][0]];
        }
        return res;
    }

    private boolean ifVowelString(String word) {
        return VOWEL_CHAR_SETS.contains(word.charAt(0)) && VOWEL_CHAR_SETS.contains(word.charAt(word.length() - 1));
    }
}

References

2559. Count Vowel Strings in Ranges