239. Sliding Window Maximum

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