class Solution {public:    int characterReplacement(string s, int k) {        int left = 0;        int maxLen = 0;        int tmpK = k;        for(int right = 1; right < s.size(); right++){            if(s[right] != s[left]){                tmpK--;                if(tmpK < 0){                    do{                        left++;                    }while(s[left] == s[left-1]);                    right = left;                    tmpK = k;                }            }            if(maxLen < right - left + 1){                maxLen = right - left + 1;            }        }        int backLen = s.size() - left + tmpK;        if(maxLen < backLen){            maxLen = backLen;        }        if(maxLen > s.size()){            maxLen = s.size();        }        return maxLen;    }};