727-1

class Solution {
public:
    string minWindow(string s, string t) {
        int sindex = 0, tindex = 0, slen = s.length(), tlen = t.length(), start = -1, len = slen;
        while(sindex < slen) {
            if(s[sindex] == t[tindex]) {
                if(++tindex == tlen) {
                    //check feasibility from left to right of T
                    int end = sindex+1;
                    //check optimization from right to left of T
                    while(--tindex >= 0) {
                        while(s[sindex--] != t[tindex]);
                    }
                    ++sindex;
                    ++tindex;
                    //record the current smallest candidate
                    if(end - sindex < len) {
                        len = end - sindex;
                        start = sindex;
                    }
                }
            }
            ++sindex;
        }
        return (start == -1) ? "" : s.substr(start, len);
    }
};