Longest Substring with At Most K Distinct Characters(LeetCode 340):

Problem

Given a string s and an integer k, return the length of the longest substring of s that contains at most k distinct characters.

 

Example 1:

Input: s = "eceba", k = 2
Output: 3
Explanation: The substring is "ece" with length 3.

Example 2:

Input: s = "aa", k = 1
Output: 2
Explanation: The substring is "aa" with length 2.

 

Constraints:

  • 1 <= s.length <= 5 * 104
  • 0 <= k <= 50