Given a string s, return the maximum length of a substring such that it contains at most two occurrences of each character.
Example 1:
Input: s = "bcbbbcba"
Output: 4
Explanation:
The following substring has a length of 4 and contains at most two occurrences of each character:"bcbbbcba".Example 2:
Input: s = "aaaa"
Output: 2
Explanation:
The following substring has a length of 2 and contains at most two occurrences of each character:"aaaa".
Constraints:
2 <= s.length <= 100s consists only of lowercase English letters."bcbbbcba" "aaaa"