LeetCode 424 - Longest Repeating Character Replacement - 2023.1014 solution

class Solution:
    def characterReplacement(self, s: str, k: int) -> int:
        longest = 0

        for character in 'ABCDEFGHIJKLMNOPQRSTUVWXYZ':
            l = 0
            k_used = 0
            for r in range(len(s)):
                if s[r] != character:
                    k_used += 1
                if k_used <= k:
                    longest = max(longest, r - l + 1)
                while k_used > k:
                    if s[l] != character:
                        k_used -= 1
                    l += 1

        return longest