# https://leetcode.com/problems/longest-repeating-character-replacement/
# 424. Longest Repeating Character Replacement
# Given a string s that consists of only uppercase English letters,
# you can perform at most k operations on that string.
# In one operation, you can choose any character of the string and change it
# to any other uppercase English character.
# Find the length of the longest sub-string containing all repeating letters
# you can get after performing the above operations.
# Note:
# Both the string's length and k will not exceed 104.
# Example 1:
# Input:
# s = "ABAB", k = 2
# Output: 4
# Explanation:
# Replace the two 'A's with two 'B's or vice versa.
# Example 2:
# Input:
# s = "AABABBA", k = 1
# Output: 4
# Explanation:
# Replace the one 'A' in the middle with 'B' and form "AABBBBA".
# The substring "BBBB" has the longest repeating letters, which is 4.
