用deque维持单调递减队列
deque中存入数组位置
class Solution {
public:
vector<int> maxSlidingWindow(vector<int>& nums, int k) {
deque<int> dq;
vector<int> res;
for (int i = 0; i < nums.size(); ++i) {
while (!dq.empty() && nums[dq.back()] < nums[i]) {
dq.pop_back();
}
dq.push_back(i);
if (i - dq.front() >= k) {
dq.pop_front();
}
if (i >= k - 1) {
res.push_back(nums[dq.front()]);
}
}
return res;
}
};