Daily Coading Problem Challenge
This problem was asked by Amazon.
Given an integer k and a string s, find the length of the longest substring that contains at most k distinct characters.
For example, given s = "abcba" and k = 2, the longest substring with k distinct characters is "bcb".
Input: S = "eceba" and k = 3 Output: 4 Explanation: T = "eceb"
Input: S = "WORLD" and k = 4 Output: 4 Explanation: T = "WORL" or "ORLD"