[leetcode] 1624. Largest Substring Between Two Equal Characters

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.

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.

分析

题目的意思是:移除两个相同字符串后剩下子串的最大长度,很显然分别移除位于最左的相同字符串就可以了。因此用一个字典保存字符串最左边的位置,当遍历到相同的字符串维护更新最大长度res就行了。

代码

class Solution:
    def maxLengthBetweenEqualCharacters(self, s: str) -> int:
        d={}
        res=-1
        for i in range(len(s)):
            if(s[i] in d):
                res=max(res,i-d[s[i]]-1)
            else:
                d[s[i]]=i
        return res

参考文献

[LeetCode] 3 Solutions | Naive | Two Pass | One Pass O(n)

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转载自blog.csdn.net/w5688414/article/details/109348949