2062. Count Vowel Substrings of a String

Problem

A substring is a contiguous (non-empty) sequence of characters within a string.

A vowel substring is a substring that only consists of vowels ('a', 'e', 'i', 'o', and 'u') and has all five vowels present in it.

Given a string word, return **the number of *vowel substrings* in** word.

  Example 1:

Input: word = "aeiouu"
Output: 2
Explanation: The vowel substrings of word are as follows (underlined):
- "aeiouu"
- "aeiouu"

Example 2:

Input: word = "unicornarihan"
Output: 0
Explanation: Not all 5 vowels are present, so there are no vowel substrings.

Example 3:

Input: word = "cuaieuouac"
Output: 7
Explanation: The vowel substrings of word are as follows (underlined):
- "cuaieuouac"
- "cuaieuouac"
- "cuaieuouac"
- "cuaieuouac"
- "cuaieuouac"
- "cuaieuouac"
- "cuaieuouac"

  Constraints:

• 1 <= word.length <= 100

• word consists of lowercase English letters only.

Solution (Java)

class Solution {
    public int countVowelSubstrings(String word) {
        int count = 0;
        Set<Character> vowels = new HashSet<>(Arrays.asList('a', 'e', 'i', 'o', 'u'));
        Set<Character> window = new HashSet<>();
        for (int i = 0; i < word.length(); i++) {
            window.clear();
            if (vowels.contains(word.charAt(i))) {
                window.add(word.charAt(i));
                for (int j = i + 1; j < word.length(); j++) {
                    if (!vowels.contains(word.charAt(j))) {
                        break;
                    } else {
                        window.add(word.charAt(j));
                        if (window.size() == 5) {
                            count++;
                        }
                    }
                }
            }
        }
        return count;
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).