leetcode+从左到右每一个区间里的最大数，双向单调队列

https://leetcode.com/problems/sliding-window-maximum/description/

//双向单调队列
class Solution {
public:
    vector maxSlidingWindow(vector& nums, int k) {
        //双向队列是从大到小的 单调队列
        vector res;
        deque Q;
        for(int i=0; i= k-1) res.push_back(nums[Q.front()]);
        }
        return res;
    }
};