#424

Longest Repeating Character Replacement

medium· Sliding Windowruns: 0

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.

wpm 0acc 100%time 0:000 / 490

class Solution:
    def characterReplacement(self, s: str, k: int) -> int:
        count = {}
        left = 0
        max_freq = 0
        longest = 0
        for right in range(len(s)):
            count[s[right]] = count.get(s[right], 0) + 1
            max_freq = max(max_freq, count[s[right]])
            while (right - left + 1) - max_freq > k:
                count[s[left]] -= 1
                left += 1
            longest = max(longest, right - left + 1)
        return longest

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