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.
Example 4:
Input: s = "cabbac" Output: 4 Explanation: The optimal substring here is "abba". Other non-optimal substrings include "bb" and "".
Constraints:
1 <= s.length <= 300scontains only lowercase English letters.