Sword To Offer 064 - 滑动窗口的最大值

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