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, at most k times. Return the length of the longest substring containing the same letter after performing the operations.

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Pythontime O(n) · space O(1)

def characterReplacement(s: str, k: int) -> int:
    count = {}
    l = best = maxCount = 0
    for r, c in enumerate(s):
        count[c] = count.get(c, 0) + 1
        maxCount = max(maxCount, count[c])
        if (r - l + 1) - maxCount > k:
            count[s[l]] -= 1
            l += 1
        best = max(best, r - l + 1)
    return best

Next upPermutation in String

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