class Solution {
public:
    vector<int> maxInWindows(vector<int>& nums, int k) {
        vector<int> res;
    deque<int> q;
    for(int i=0;i < nums.size();i++){
        if(!q.empty()&&q.front()<i-k+1) q.pop_front();
        while(!q.empty()&&nums[q.back()]<nums[i]) q.pop_back();
        q.push_back(i);
        if(i-k+1>=0) res.push_back(nums[q.front()]);
    }
    return res;
    }
};