jan2.java

class Solution {
    public int[] vowelStrings(String[] words, int[][] queries) {
        Set<Character> vowels=new HashSet<>();
        vowels.add('a');
        vowels.add('e');
        vowels.add('i');
        vowels.add('o');
        vowels.add('u');
        int[] prefixSum=new int[words.length+1];
        int[] result=new int[queries.length];
        for(int i=0;i<words.length;i++){
            String word=words[i];
            if(vowels.contains(word.charAt(0)) && vowels.contains(word.charAt(word.length()-1))){
                prefixSum[i+1]=prefixSum[i]+1;
            }
            else{
                prefixSum[i+1]=prefixSum[i];
            }
        }
        int index=0;
        for(int[] query:queries){
            int leftRange=query[0];
            int rightRange=query[1];
           result[index++]=prefixSum[rightRange+1]-prefixSum[leftRange];
        }
        return result;
    }
}