1839. Longest Substring Of All Vowels in Order

Problem

A string is considered beautiful if it satisfies the following conditions:

• Each of the 5 English vowels ('a', 'e', 'i', 'o', 'u') must appear at least once in it.

• The letters must be sorted in alphabetical order (i.e. all 'a's before 'e's, all 'e's before 'i's, etc.).

For example, strings "aeiou" and "aaaaaaeiiiioou" are considered beautiful, but "uaeio", "aeoiu", and "aaaeeeooo" are not beautiful.

Given a string word consisting of English vowels, return **the *length of the longest beautiful substring* of word. If no such substring exists, return **0.

A substring is a contiguous sequence of characters in a string.

  Example 1:

Input: word = "aeiaaioaaaaeiiiiouuuooaauuaeiu"
Output: 13
Explanation: The longest beautiful substring in word is "aaaaeiiiiouuu" of length 13.

Example 2:

Input: word = "aeeeiiiioooauuuaeiou"
Output: 5
Explanation: The longest beautiful substring in word is "aeiou" of length 5.

Example 3:

Input: word = "a"
Output: 0
Explanation: There is no beautiful substring, so return 0.

  Constraints:

• 1 <= word.length <= 5 * 10^5

• word consists of characters 'a', 'e', 'i', 'o', and 'u'.

Solution (Java)

class Solution {
    public int longestBeautifulSubstring(String word) {
        int cnt = 1;
        int len = 1;
        int maxLen = 0;
        for (int i = 1; i != word.length(); ++i) {
            if (word.charAt(i - 1) == word.charAt(i)) {
                ++len;
            } else if (word.charAt(i - 1) < word.charAt(i)) {
                ++len;
                ++cnt;
            } else {
                cnt = 1;
                len = 1;
            }

            if (cnt == 5) {
                maxLen = Math.max(maxLen, len);
            }
        }
        return maxLen;
    }
}

Explain:

nope.

Complexity:

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