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### by Sumit Chourasia | Oct 18, 2020 | Category :coding | Tags : algorithmarraydata-structureeasyleetcode #### Largest Substring Between Two Equal Characters - Array - Easy - LeetCode

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.

``````public class Solution {
public int MaxLengthBetweenEqualCharacters(string s) {
var map = new Dictionary<char,int>();
var maxLen = -1;
for(int i=0;i<s.Length;i++){
if(map.ContainsKey(s[i])){
int diff = i - map[s[i]];
if(diff-1 > maxLen){
maxLen = diff-1;
}
}
else{