代码随想录二刷|第一章数组：滑动窗口

最小覆盖子串

c1：记录t中字符的频率
c2：记录当前滑动窗口内字符的频率

class Solution {
public:
    string minWindow(string s, string t) {
        int tot = 0;
        vector<int> c1(60), c2(60);
        for(char x : t){
            c1[getIdx(x)]++;
            if(c1[getIdx(x)] == 1) tot++;
        }
        string ans = "";
        int i = 0;
        for (int j = 0; j < s.size(); j++){
            int right = getIdx(s[j]);
            c2[right]++;
            if(c2[right] == c1[right]) tot--;
            while (i < j) {
                int left = getIdx(s[i]);
                if (c2[left] > c1[left]) {
                    c2[left]--;
                    i++;
                }
                else break;
            }
            if (tot == 0 && (ans.empty() || ans.size() > j - i + 1)) ans = s.substr(i, j - i + 1);
        }
        return ans;
    }
    int getIdx(char x) {
        return x >= 'A' && x <= 'Z' ? x - 'A' + 26 : x - 'a';
    }
};

class Solution {
public:
    string minWindow(string s, string t) {
        int tot = 0;
        vector<int> c1(60), c2(60);
        for(char x : t){
            c1[getIdx(x)]++;
            if(c1[getIdx(x)] == 1) tot++;
        }
        string ans = "";
        int i = 0;
        for (int j = 0; j < s.size(); j++){
            int right = getIdx(s[j]);
            c2[right]++;
            if(c2[right] == c1[right]) tot--;
            while (i < j && c2[getIdx(s[i])] > c1[getIdx(s[i])]){
                c2[getIdx(s[i])]--;
                i++;
            }
            // while (i < j) {
            //     int left = getIdx(s[i]);
            //     if (c2[left] > c1[left]) {
            //         c2[left]--;
            //         i++;
            //     }
            //     else break;
            // }
            if (tot == 0 && (ans.empty() || ans.size() > j - i + 1)) ans = s.substr(i, j - i + 1);
        }
        return ans;
    }
    int getIdx(char x) {
        return x >= 'A' && x <= 'Z' ? x - 'A' + 26 : x - 'a';
    }
};