class Solution{// review 438 O(N) O(1)
public:
    vector<int> findAnagrams(string s, string p){
        int n=s.size(),m=p.size();if(m>n)return{};
        int cnt[26]={},need=m;for (char c:p)++cnt[c-'a'];
        vector<int>ans;
        for(int r=0; r<n;++r){
            if(cnt[s[r]-'a']-->0)--need;
            if(r>=m && cnt[s[r-m]-'a']++>=0)++need;
            if(!need)ans.push_back(r-m+1);
        }
        return ans;
    }
};