替换后的最长重复字符

/*
 * Problem: Given a string s and an integer k, you can change any character in the string
 * to any other uppercase English letter up to k times. Return the length of the longest
 * substring that contains the same letter after performing the above operations.
 *
 * Approach:
 * - Use the sliding window technique to find the longest substring.
 * - Use Java Streams to manage the counting of characters.
 * - Track the maximum count of any character in the window.
 * - If the current window size minus the max count is greater than k, shrink the window.
 * - Update the maximum length whenever a valid window is found.
 */
import java.util.stream.IntStream;
 
public class Solution {
    public int characterReplacement(String s, int k) {
        int[] count = new int[26];
        int maxCount = 0, maxLength = 0;
        int left = 0;
 
        for (int right = 0; right < s.length(); right++) {
            count[s.charAt(right) - 'A']++;
            maxCount = IntStream.of(count).max().orElse(0);
 
            while (right - left + 1 - maxCount > k) {
                count[s.charAt(left) - 'A']--;
                left++;
            }
 
            maxLength = Math.max(maxLength, right - left + 1);
        }
 
        return maxLength;
    }
}