0424. Longest Repeating Character Replacement

https://leetcode.com/problems/longest-repeating-character-replacement

Description

You are given a string s and an integer k. You can choose any character of the string and change it to any other uppercase English character. You can perform this operation at most k times.

Return the length of the longest substring containing the same letter you can get after performing the above operations.

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.

Constraints:

• 1 <= s.length <= 105

• s consists of only uppercase English letters.

• 0 <= k <= s.length

ac