leetcode 日经贴，Cpp code -Sliding Window Maximum

Sliding Window Maximum

class Solution {public:    vector<int> maxSlidingWindow(vector<int>& nums, int k) {        deque<pair<int, int> > dq;        int n = nums.size();        vector<int> ans;        if (k <= 0 || k > n) {            return ans;        }        for (int i = 0; i < k - 1; ++i) {            while (!dq.empty() && dq.back().second <= nums[i]) {                dq.pop_back();            }            dq.push_back(make_pair(i, nums[i]));        }        for (int i = k - 1; i < n; ++i) {            //remove the useless element            while (!dq.empty() && dq.front().first + k <= i) {                dq.pop_front();            }            while (!dq.empty() && dq.back().second <= nums[i]) {                dq.pop_back();            }            dq.push_back(make_pair(i, nums[i]));            ans.push_back(dq.front().second);        }        return ans;    }};