public class Solution
extends Object
1371 - Find the Longest Substring Containing Vowels in Even Counts\.
Medium
Given the string `s`, return the size of the longest substring containing each vowel an even number of times. That is, 'a', 'e', 'i', 'o', and 'u' must appear an even number of times.
**Example 1:**
**Input:** s = "eleetminicoworoep"
**Output:** 13
**Explanation:** The longest substring is "leetminicowor" which contains two each of the vowels: **e** , **i** and **o** and zero of the vowels: **a** and **u**.
**Example 2:**
**Input:** s = "leetcodeisgreat"
**Output:** 5
**Explanation:** The longest substring is "leetc" which contains two e's.
**Example 3:**
**Input:** s = "bcbcbc"
**Output:** 6
**Explanation:** In this case, the given string "bcbcbc" is the longest because all vowels: **a** , **e** , **i** , **o** and **u** appear zero times.
**Constraints:**
* `1 <= s.length <= 5 x 10^5`
* `s` contains only lowercase English letters.