剑指offer——68队列的最大值

 1 class Solution {
 2 public:
 3     vector<int> maxInWindows(const vector<int>& num, unsigned int size) {
 4         if (num.size() == 0 || size <= 0 || size > num.size())return {};
 5         vector<int>res;
 6         deque<int>List;
 7         int L = 0, R = 0;
 8         while (R < num.size()) {
 9             while (!List.empty() && num[List.back()] < num[R])List.pop_back();
10             List.push_back(R);
11             ++R;
12             if (R < size)continue;
13             if (R == size)res.push_back(num[List.front()]);//第一个窗口
14             else {//其他窗口
15                 if (List.front() == L)List.pop_front();//最大数就是去除的左数，则删除该数
16                 ++L;
17                 res.push_back(num[List.front()]);
18             }
19         }
20         return res;
21     }
22 };