[滑动窗口] leetcode 424 Longest Repeating Character Replacement

Posted 2022-07-02 fish1996

problem:https://leetcode.com/problems/longest-repeating-character-replacement/

        维护一个最多包含k个额外字符的滑动窗口。需要记录当前出现次数最多字符的出现次数来判断窗口是否合法，如果超过了，就把首指针向后挪一位，同时更新最多出现次数。对每个合法窗口，取其中的最大值。

class Solution 
public:
    int characterReplacement(string s, int k) 
        
        int begin = 0;
        int res = 0;
        int maxLen = 0;
        vector<int> count(26, 0);
        for(int i = 0;i < s.size();i++) // end
        
            count[s[i] - ‘A‘]++;
            maxLen = max(maxLen, count[s[i] - ‘A‘]);
            int len = i - begin + 1;
            if(len > maxLen + k)
            
                count[s[begin] - ‘A‘]--;
                begin++;
                maxLen = *max_element(count.begin(), count.end());
            
       //     cout << res << " ";
            res = max(res, i - begin + 1);
        
        return res;
    
;