57 lines
1.6 KiB
C++

// Source : https://leetcode.com/problems/largest-substring-between-two-equal-characters/
// Author : Hao Chen
// Date : 2021-03-24
/*****************************************************************************************************
*
* 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.
******************************************************************************************************/
class Solution {
public:
int maxLengthBetweenEqualCharacters(string s) {
int pos[26]={0};
int longest = -1 ;
for (int i=0; i<s.size(); i++){
int idx = s[i] -'a';
if (pos[idx] == 0) pos[idx] = i + 1;
else longest = max(longest, i - pos[idx]);
}
return longest;
}
};