Largest Substring Between Two Equal Characters

You are 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.