# Largest Substring Between Two Equal Characters

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 <= 300
• s contains only lowercase English letters.

Solution:

```class Solution {
public int maxLengthBetweenEqualCharacters(String s) {
Integer[][] map = new Integer[26][2];
for (int i = 0; i < s.length(); i ++) {
int c = s.charAt(i) - 'a';
if (map[c][0] == null) {
map[c][0] = i;
map[c][1] = i;
} else {
map[c][1] = i;
}
}
int max = -1;
for (int i = 0; i < 26; i ++) {
if (map[i][0] != null) {
max = Math.max(max, map[i][1] - map[i][0] - 1);
}
}
return max;
}
}```