queue

 vector <int> max_of_subarrays(int *arr, int n, int k)
    {
        // your code here
        for(int i=0;i<k;i++) add(arr[i]);
        vector<int>ans;
        ans.push_back(mx());

        for(int i=k;i<n;i++){
            del(arr[i-k]);
            add(arr[i]);
            ans.push_back(mx());
        }
        return ans;
    }
private:
    deque<int>dq;
  void add(int ele){
      while(!dq.empty() and dq.back()<ele) dq.pop_back();
      dq.push_back(ele);
  }
  void del(int ele){
      if(!dq.empty() and dq.front()==ele) dq.pop_front();
  }
  int mx(){
      return dq.front();
  }