Count Vowel Strings in Ranges

Problem Description:

You are given:

1. An array of strings words: These are lowercase English words.
2. A list of queries queries: Each query is a range [li, ri].

Task:
For each query [li, ri], count how many words in the range (from index li to ri, inclusive) start and end with a vowel.

What are vowels?

The vowels are 'a', 'e', 'i', 'o', and 'u'.

Output:

Return an array ans where:

• ans[i] is the answer to the i-th query.

---

Example 1:

Input: words = ["aba", "bcb", "ece", "aa", "e"],           queries = [[0, 2], [1, 4], [1, 1]]
Output: [2, 3, 0]

Explanation:

Words starting and ending with vowels:
"aba", "ece", "aa", "e".

Query Results:

• For [0, 2]:
  The range contains "aba" and "ece", so the result is 2.
• For [1, 4]:
  The range contains "ece", "aa", "e", so the result is 3.
• For [1, 1]:
  No word in this range satisfies the condition, so the result is 0.

Example 2:

Input: words = ["a","e","i"],                       queries = [[0,2],[0,1],[2,2]]

Output: [2, 3, 0]

Explanation:

All words start and end with vowels.

Query Results:

• For [0, 2]:
  All words in this range ("a", "e", "i") satisfy the condition, so the result is 3.
• For [0, 1]:
  The range contains "a" and "e", so the result is 2.
• For [2, 2]:
  The range contains "i", so the result is 1.

Constraints:

• Number of words (words.length): Up to $10^5$.
• Length of a single word (words[i].length): Up to $40$.
• Total characters in all words combined: Up to $3 \times 10^5$.
• Number of queries (queries.length): Up to $10^5$.
• Query range: Always valid, i.e., $0 \leq l_i \leq r_i < \text{words.length}$.

— Written by Saurabh Patil • B.Tech CSE • Software Developer