1624. Largest Substring Between Two Equal Characters

1624. Largest Substring Between Two Equal Characters #

题目 #

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.

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.

题目大意 #

给你一个字符串 s,请你返回 两个相同字符之间的最长子字符串的长度 ,计算长度时不含这两个字符。如果不存在这样的子字符串,返回 -1 。子字符串 是字符串中的一个连续字符序列。

解题思路 #

  • 简单题。取每个字符,扫描一次字符串,如果在字符串中还能找到相同的字符,则返回最末尾的那个字符,计算这两个字符之间的距离。取最末尾的字符是为了让两个相同的字符距离最长。扫描字符串过程中动态维护最长长度。如果字符串中不存在 2 个相同的字符,则返回 -1 。

代码 #

package leetcode

import "strings"

func maxLengthBetweenEqualCharacters(s string) int {
	res := -1
	for k, v := range s {
		tmp := strings.LastIndex(s, string(v))
		if tmp > 0 {
			if res < tmp-k-1 {
				res = tmp - k - 1
			}
		}
	}
	return res
}

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