没什么好说的，滑就是了……

class Solution {
public:
    vector<int> findAnagrams(string s, string p) {
        vector<int> res;
        vector<int> dic(26),window(26);
        for(char c:p)
            ++dic[c-'a'];
        for(int pl=0,pr=0;pr<s.size();++pr)
        {
            ++window[s[pr]-'a'];
            while(pr+1>pl+p.size())
                --window[s[pl++]-'a'];
            if(window==dic)
                res.push_back(pl);
        }
        return res;
    }
};