public class Solution
extends Object
1624 - Largest Substring Between Two Equal Characters\.
Easy
Given a string `s`, return _the length of the longest substring between two equal characters, excluding the two characters._ If there is no such substring return `-1`.
A **substring** is a contiguous sequence of characters within a string.
**Example 1:**
**Input:** s = "aa"
**Output:** 0
**Explanation:** The optimal substring here is an empty substring between the two `'a's`.
**Example 2:**
**Input:** s = "abca"
**Output:** 2
**Explanation:** The optimal substring here is "bc".
**Example 3:**
**Input:** s = "cbzxy"
**Output:** -1
**Explanation:** There are no characters that appear twice in s.
**Constraints:**
* `1 <= s.length <= 300`
* `s` contains only lowercase English letters.