0424. Longest Repeating Character Replacement

# 424. Longest Repeating Character Replacement#

## 题目 #

Given a string that consists of only uppercase English letters, you can replace any letter in the string with another letter at most k times. Find the length of a longest substring containing all repeating letters you can get after performing the above operations.

Note:

Both the string’s length and k will not exceed 10^4.

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.

``````

## 代码 #

``````
package leetcode

func characterReplacement(s string, k int) int {
res, left, counter, freq := 0, 0, 0, make([]int, 26)
for right := 0; right < len(s); right++ {
freq[s[right]-'A']++
counter = max(counter, freq[s[right]-'A'])
for right-left+1-counter > k {
freq[s[left]-'A']--
left++
}
res = max(res, right-left+1)
}
return res
}

func max(a int, b int) int {
if a > b {
return a
}
return b
}

``````

Sep 6, 2020