Longest Repeating Character Replacement

You may change at most k characters of s to any letters. Return the length of the longest substring that can be made of one repeated letter.

For s = "AABABBA" and k = 1 the answer is 4 (change one A or B to get "AAAA" or "BBBB" within a window).

The starter code counts the letters of every substring from scratch. It is correct but too slow for long strings.

Examples

Example 1

Input:

character_replacement('AABABBA', 1)

Output:

4

Example 2

Input:

character_replacement('ABAB', 2)

Output:

4

Constraints

• 0 <= len(s) <= 200000
• 0 <= k <= 200000
• s contains upper-case letters.