Longest Substring with At Most Two Distinct Characters(LeetCode 159):

Problem

Given a string s, return the length of the longest substring that contains at most two distinct characters.

 

Example 1:

Input: s = "eceba"
Output: 3
Explanation: The substring is "ece" which its length is 3.

Example 2:

Input: s = "ccaabbb"
Output: 5
Explanation: The substring is "aabbb" which its length is 5.

 

Constraints:

  • 1 <= s.length <= 105
  • s consists of English letters.