LeetCode_424_替换后的最长字符串

class Solution {
    public int characterReplacement(String s, int k) {
        int left =0,right=0;
        int maxLength = -1;
        int result = 0;
        char[] charNums =  new char[256];
        while (right<s.length()) {
            char cur = s.charAt(right);
            charNums[cur]++;
            maxLength = Math.max(maxLength, charNums[cur]);
            while ((right-left + 1 - maxLength) > k) {
                charNums[s.charAt(left++)]--;
            }
            result = Math.max(result, right - left + 1);
            right++;
        }
        return result;
    }
}