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1624. Largest Substring Between Two Equal Characters

Difficulty Topics

Description

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.

Solution

largest-substring-between-two-equal-characters.py
class Solution:
    def maxLengthBetweenEqualCharacters(self, S: str) -> int:

        d = collections.defaultdict(list)

        for i, s in enumerate(S):
            d[s].append(i)

        return max(d[i][-1] - d[i][0] - 1 for i in d)